diff --git a/Cargo.lock b/Cargo.lock
index 0bac83e..1d80070 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1,5 +1,13 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
+[[package]]
+name = "ansi_term"
+version = "0.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "winapi 0.3.9 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "atty"
 version = "0.2.14"
@@ -15,6 +23,11 @@ name = "autocfg"
 version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "bitflags"
+version = "1.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "bstr"
 version = "0.2.13"
@@ -42,6 +55,20 @@ dependencies = [
  "time 0.1.43 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "clap"
+version = "2.33.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "ansi_term 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "atty 0.2.14 (registry+https://github.com/rust-lang/crates.io-index)",
+ "bitflags 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "strsim 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "textwrap 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "unicode-width 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "vec_map 0.8.2 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "colored"
 version = "2.0.0"
@@ -135,11 +162,6 @@ dependencies = [
  "autocfg 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
-[[package]]
-name = "pargs"
-version = "0.2.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-
 [[package]]
 name = "proc-macro2"
 version = "1.0.19"
@@ -166,13 +188,13 @@ dependencies = [
 
 [[package]]
 name = "rust_ledger"
-version = "0.4.1"
+version = "0.4.2"
 dependencies = [
  "chrono 0.4.15 (registry+https://github.com/rust-lang/crates.io-index)",
+ "clap 2.33.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "colored 2.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "csv 1.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "monee 0.0.5 (registry+https://github.com/rust-lang/crates.io-index)",
- "pargs 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.115 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_yaml 0.8.13 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -211,6 +233,11 @@ dependencies = [
  "yaml-rust 0.4.4 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "strsim"
+version = "0.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "syn"
 version = "1.0.38"
@@ -221,6 +248,14 @@ dependencies = [
  "unicode-xid 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "textwrap"
+version = "0.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "unicode-width 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "time"
 version = "0.1.43"
@@ -230,11 +265,21 @@ dependencies = [
  "winapi 0.3.9 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "unicode-width"
+version = "0.1.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "unicode-xid"
 version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "vec_map"
+version = "0.8.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "winapi"
 version = "0.3.9"
@@ -263,11 +308,14 @@ dependencies = [
 ]
 
 [metadata]
+"checksum ansi_term 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ee49baf6cb617b853aa8d93bf420db2383fab46d314482ca2803b40d5fde979b"
 "checksum atty 0.2.14 (registry+https://github.com/rust-lang/crates.io-index)" = "d9b39be18770d11421cdb1b9947a45dd3f37e93092cbf377614828a319d5fee8"
 "checksum autocfg 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "f8aac770f1885fd7e387acedd76065302551364496e46b3dd00860b2f8359b9d"
+"checksum bitflags 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "cf1de2fe8c75bc145a2f577add951f8134889b4795d47466a54a5c846d691693"
 "checksum bstr 0.2.13 (registry+https://github.com/rust-lang/crates.io-index)" = "31accafdb70df7871592c058eca3985b71104e15ac32f64706022c58867da931"
 "checksum byteorder 1.3.4 (registry+https://github.com/rust-lang/crates.io-index)" = "08c48aae112d48ed9f069b33538ea9e3e90aa263cfa3d1c24309612b1f7472de"
 "checksum chrono 0.4.15 (registry+https://github.com/rust-lang/crates.io-index)" = "942f72db697d8767c22d46a598e01f2d3b475501ea43d0db4f16d90259182d0b"
+"checksum clap 2.33.3 (registry+https://github.com/rust-lang/crates.io-index)" = "37e58ac78573c40708d45522f0d80fa2f01cc4f9b4e2bf749807255454312002"
 "checksum colored 2.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "b3616f750b84d8f0de8a58bda93e08e2a81ad3f523089b05f1dffecab48c6cbd"
 "checksum csv 1.1.3 (registry+https://github.com/rust-lang/crates.io-index)" = "00affe7f6ab566df61b4be3ce8cf16bc2576bca0963ceb0955e45d514bf9a279"
 "checksum csv-core 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)" = "2b2466559f260f48ad25fe6317b3c8dac77b5bdb5763ac7d9d6103530663bc90"
@@ -281,7 +329,6 @@ dependencies = [
 "checksum monee 0.0.5 (registry+https://github.com/rust-lang/crates.io-index)" = "10185d7e26610b2ca56d56254e26b1654bbe964e7bd94be07d726f964d19d2db"
 "checksum num-integer 0.1.43 (registry+https://github.com/rust-lang/crates.io-index)" = "8d59457e662d541ba17869cf51cf177c0b5f0cbf476c66bdc90bf1edac4f875b"
 "checksum num-traits 0.2.12 (registry+https://github.com/rust-lang/crates.io-index)" = "ac267bcc07f48ee5f8935ab0d24f316fb722d7a1292e2913f0cc196b29ffd611"
-"checksum pargs 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "ab9021fd518ce95acf9c8f7c325187d456268464b07965d7ee3e96adf30609e3"
 "checksum proc-macro2 1.0.19 (registry+https://github.com/rust-lang/crates.io-index)" = "04f5f085b5d71e2188cb8271e5da0161ad52c3f227a661a3c135fdf28e258b12"
 "checksum quote 1.0.7 (registry+https://github.com/rust-lang/crates.io-index)" = "aa563d17ecb180e500da1cfd2b028310ac758de548efdd203e18f283af693f37"
 "checksum regex-automata 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)" = "ae1ded71d66a4a97f5e961fd0cb25a5f366a42a41570d16a763a69c092c26ae4"
@@ -289,9 +336,13 @@ dependencies = [
 "checksum serde 1.0.115 (registry+https://github.com/rust-lang/crates.io-index)" = "e54c9a88f2da7238af84b5101443f0c0d0a3bbdc455e34a5c9497b1903ed55d5"
 "checksum serde_derive 1.0.115 (registry+https://github.com/rust-lang/crates.io-index)" = "609feed1d0a73cc36a0182a840a9b37b4a82f0b1150369f0536a9e3f2a31dc48"
 "checksum serde_yaml 0.8.13 (registry+https://github.com/rust-lang/crates.io-index)" = "ae3e2dd40a7cdc18ca80db804b7f461a39bb721160a85c9a1fa30134bf3c02a5"
+"checksum strsim 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)" = "8ea5119cdb4c55b55d432abb513a0429384878c15dde60cc77b1c99de1a95a6a"
 "checksum syn 1.0.38 (registry+https://github.com/rust-lang/crates.io-index)" = "e69abc24912995b3038597a7a593be5053eb0fb44f3cc5beec0deb421790c1f4"
+"checksum textwrap 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)" = "d326610f408c7a4eb6f51c37c330e496b08506c9457c9d34287ecc38809fb060"
 "checksum time 0.1.43 (registry+https://github.com/rust-lang/crates.io-index)" = "ca8a50ef2360fbd1eeb0ecd46795a87a19024eb4b53c5dc916ca1fd95fe62438"
+"checksum unicode-width 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)" = "9337591893a19b88d8d87f2cec1e73fad5cdfd10e5a6f349f498ad6ea2ffb1e3"
 "checksum unicode-xid 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "f7fe0bb3479651439c9112f72b6c505038574c9fbb575ed1bf3b797fa39dd564"
+"checksum vec_map 0.8.2 (registry+https://github.com/rust-lang/crates.io-index)" = "f1bddf1187be692e79c5ffeab891132dfb0f236ed36a43c7ed39f1165ee20191"
 "checksum winapi 0.3.9 (registry+https://github.com/rust-lang/crates.io-index)" = "5c839a674fcd7a98952e593242ea400abe93992746761e38641405d28b00f419"
 "checksum winapi-i686-pc-windows-gnu 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ac3b87c63620426dd9b991e5ce0329eff545bccbbb34f3be09ff6fb6ab51b7b6"
 "checksum winapi-x86_64-pc-windows-gnu 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"
diff --git a/Cargo.toml b/Cargo.toml
index fee7d9d..ea21d4f 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "rust_ledger"
-version = "0.4.1"
+version = "0.4.2"
 authors = ["ebcrowder <ebcrowder@gmail.com>"]
 edition = "2018"
 license = "GPL-3.0"
@@ -15,7 +15,7 @@ readme = "README.md"
 serde_yaml = "0.8.13"
 serde = { version = "1.0.114", features = ["derive"] }
 csv = "1.1.3"
-pargs = "0.2.1" 
 colored = "2.0.0"
 monee = "0.0.5"
 chrono = { version = "0.4", features = ["serde"] }
+clap = "2.33.3"
diff --git a/README.md b/README.md
index 66eebc1..5e4f89c 100644
--- a/README.md
+++ b/README.md
@@ -17,20 +17,23 @@ As a former CPA, I could not resist building my own accounting system.
 - Includes a tool to convert `csv` files to `yaml` format
 
 ### Contributing
+
 - See `CODE_OF_CONDUCT.md` for fundamental guidelines
 - PRs, issues and feature requests are welcome and encouraged
-- Join us on Matrix (#rust_ledger:matrix.org) at https://matrix.to/#/!dYISGJYNNiZcUrxhcm:matrix.org?via=matrix.org 
+- Join us on Matrix (#rust_ledger:matrix.org) at https://matrix.to/#/!dYISGJYNNiZcUrxhcm:matrix.org?via=matrix.org
 
 ### Install
 
-#### From Cargo 
+#### From Cargo
 
 `cargo install rust_ledger`
 
 #### Binaries for Linux, macOS, and Windows
+
 We distribute binaries for the above platforms. See [releases](https://github.com/ebcrowder/rust_ledger/releases) for a complete list by version.
 
 Additionally, we currently ship binaries through the following package managers:
+
 - Arch Linux AUR - rust_ledger-bin
 
 #### Build from Source
@@ -43,42 +46,55 @@ Alternatively, clone this repo and do the following:
 
 ### Usage
 
-`rust_ledger -f LEDGER_FILE_PATH COMMAND -o OPTION`
+`rust_ledger --help` will provide a menu of all available commands and optional arguments.
+
+```bash
+rust_ledger <version>
+Eric Crowder <ebcrowder@gmail.com>
+
+USAGE:
+    rust_ledger [SUBCOMMAND]
+
+FLAGS:
+    -h, --help       Prints help information
+    -V, --version    Prints version information
+
+SUBCOMMANDS:
+    account     account module
+    balance     balance module
+    csv         csv module
+    help        Prints this message or the help of the given subcommand(s)
+    register    register module
+```
+
+`rust_ledger COMMAND -f LEDGER_FILE_PATH`
 
 LEDGER_FILE_PATH (denoted by `-f`) - relative path to location of yaml ledger file
 
-  - Optionally, the ledger file path can be set via the environment variable `RLEDGER_FILE` in lieu of specifying whenever the program is invoked.
-  - If `-f` is provided with a file path the file provided will be used instead of any `RLEDGER_FILE` set.
+- Optionally, the ledger file path can be set via the environment variable `RLEDGER_FILE` in lieu of specifying whenever the program is invoked.
+- If `-f` is provided with a file path the file provided will be used instead of any `RLEDGER_FILE` set.
 
 ```
-RLEDGER_FILE=~/rledger.yaml rust_ledger balances
+RLEDGER_FILE=~/rledger.yaml rust_ledger balance
 ```
 
 `RLEDGER_FILE` can be set as a system or user environment variable.
 
 ```
-export RLEDGER_FILE="$HOME/rledger.yaml"
+export RLEDGER_FILE=$HOME/rledger.yaml
 ```
 
-COMMAND - ledger command (account, balance, register, or csv)
-
-OPTION (denoted by `-o`) - allows you to filter the output of the `register` command by account type. For example, if you wish to only see "expense" transactions in the output, you would pass in `expense` as the option here. Additionally, the csv tool uses this parameter for specifying the csv file to be parsed.
-
-GROUP (denoted by `-g`) - allows you to group the output of the `register` command by `year` or `month`. 
-
-OFFSET (denoted by `-s`) - required for csv tool. Specifies the offsetting account that each transaction should be posted against. 
-
 ### Environment Variables
 
 `RLEDGER_FILE` - Path to rledger file. ex: `RLEDGER_FILE=~/rledger.yaml`
 
 `NO_COLOR` - Disables color output. ex: `NO_COLOR=true`
 
-### Features
+## Features
 
-#### Transactions
+### Transactions
 
-Transactions can be expressed in two different ways. One is a "simplified" format for transactions that only impact two accounts: 
+Transactions can be expressed in two different ways. One is a "simplified" format for transactions that only impact two accounts:
 
 ```yaml
 - date: 2020-01-01
@@ -88,9 +104,9 @@ Transactions can be expressed in two different ways. One is a "simplified" forma
   account: expense:expense_general
 ```
 
-The sign (debit / credit) associated with the `offset_account` value is the opposite of the sign of the value contained in `amount` field.  
+The sign (debit / credit) associated with the `offset_account` value is the opposite of the sign of the value contained in `amount` field.
 
-In the above example transaction, since `expense_general` was debited by 200, the `credit_card_amex` account will be credited by the same amount. 
+In the above example transaction, since `expense_general` was debited by 200, the `credit_card_amex` account will be credited by the same amount.
 
 Transactions that involve more than two accounts are expressed in the following manner:
 
@@ -106,63 +122,113 @@ Transactions that involve more than two accounts are expressed in the following
       account: liability:credit_card_amex
 ```
 
-Transactions that only involve two accounts can also be expressed in the above format. 
+Transactions that only involve two accounts can also be expressed in the above format.
 
-### Test
+## Test
 
 - `cargo test`
 
-### API
+## API
+
+### account
+
+```
+rust_ledger-account
+account module
+
+USAGE:
+    rust_ledger account [OPTIONS]
 
-- account
-  - lists accounts
-  - example output:
+FLAGS:
+    -h, --help       Prints help information
+    -V, --version    Prints version information
 
+OPTIONS:
+    -f, --filename <filename>    location of ledger file
 ```
- Account                      
+
+- lists accounts
+- example output:
+
+```
+ Account
 ---------------------------------------
-asset:cash_checking         
-asset:cash_savings          
-liability:credit_card_amex  
-equity:equity               
-expense:grocery             
-expense:general             
-expense:mortgage            
+asset:cash_checking
+asset:cash_savings
+liability:credit_card_amex
+equity:equity
+expense:grocery
+expense:general
+expense:mortgage
 income:general
 ```
 
-- balance
-  - lists account balances to date
-  - example output:
+### balance
+
+```
+rust_ledger-balance
+balance module
+
+USAGE:
+    rust_ledger balance [OPTIONS]
+
+FLAGS:
+    -h, --help       Prints help information
+    -V, --version    Prints version information
+
+OPTIONS:
+    -f, --filename <filename>    location of ledger file
+```
+
+- lists account balances to date
+- example output:
 
 ```
- Account                       Balance             
+ Account                       Balance
 ---------------------------------------
 asset
-  asset:cash_checking          $ -700.00           
-  asset:cash_savings           $ 1000.00           
+  asset:cash_checking          $ -700.00
+  asset:cash_savings           $ 1000.00
 liability
-  liability:credit_card_amex   $ -455.00           
+  liability:credit_card_amex   $ -455.00
 equity
-  equity:equity                $ -3500.00          
+  equity:equity                $ -3500.00
 expense
-  expense:grocery              $ 635.00            
-  expense:general              $ 1020.00           
-  expense:mortgage             $ 2000.00           
+  expense:grocery              $ 635.00
+  expense:general              $ 1020.00
+  expense:mortgage             $ 2000.00
 income
-  income:general               0                   
+  income:general               0
 
 ---------------------------------------
-check                          0           
+check                          0
+```
+
+### register
+
+```
+rust_ledger-register
+register module
+
+USAGE:
+    rust_ledger register [OPTIONS]
+
+FLAGS:
+    -h, --help       Prints help information
+    -V, --version    Prints version information
+
+OPTIONS:
+    -f, --filename <filename>    location of ledger file
+    -g, --group <group>          group register output by value
+    -o, --option <option>        filter output by optional value
 ```
 
-- register
-  - lists general ledger transactions to date
-  - can filter output by any field via optional parameter
-  - example output:
+- lists general ledger transactions to date
+- can filter output by any field via optional parameter
+- example output:
 
 ```
-Date       Description             Accounts              
+Date       Description             Accounts
 ---------------------------------------------------------------------------------
 2019-12-31 weekly groceries        grocery                  $ 455.00     $ 455.00
                                    credit_card_amex        $ -455.00            0
@@ -175,47 +241,62 @@ Date       Description             Accounts
                                    cash_checking           $ -200.00            0
 ```
 
-- csv
-  - converts `csv` files to `yaml` format expected by `rust_ledger`.
-  - should be invoked with `-f`, `-o`, and `s` arguments. These include the rust_ledger file location (unless specified via environment variable),
+### csv
+
+```
+rust_ledger-csv
+csv module
+
+USAGE:
+    rust_ledger csv [OPTIONS]
+
+FLAGS:
+    -h, --help       Prints help information
+    -V, --version    Prints version information
+
+OPTIONS:
+    -c, --csv <csv>              path of csv file
+    -f, --filename <filename>    location of ledger file
+    -o, --offset <offset>        offset account for each csv transaction
+```
+
+- converts `csv` files to `yaml` format expected by `rust_ledger`.
+- should be invoked with `-f`, `-o`, and `s` arguments. These include the rust_ledger file location (unless specified via environment variable),
   csv file location and account offset, respectively.
-  - the account offset (`s` argument) would be the offset transaction that the csv transactions should be posted against.
-  - the csv tool will look for existing transactions that have matching `description` fields and will populate the appropriate expense/income accounts
+- the account offset (`s` argument) would be the offset transaction that the csv transactions should be posted against.
+- the csv tool will look for existing transactions that have matching `description` fields and will populate the appropriate expense/income accounts
   for any matches. Non-matches will use a default of `expense:general` or `income:general`, which is determined based on the sign of the `amount` field
   contained in the transaction.
-  - **note** - prior to importing your `csv` file into the tool, you must rename the columns in the first line of the `csv` file in the following schema:
-    `"date","transaction","name","memo","amount"`.
-
-- version
-  - prints release version to `stdout`.
+- **note** - prior to importing your `csv` file into the tool, you must rename the columns in the first line of the `csv` file in the following schema:
+  `"date","transaction","name","memo","amount"`.
 
-### rust_ledger `yaml` file format
+## rust_ledger `yaml` file format
 
 - example ledger `yaml` file can be found at `examples/example.yaml`
 - rust_ledger utilizes `yaml` files in the following format:
 
 ```yaml
 accounts:
-  - account: 
-    amount:  
+  - account:
+    amount:
 
 transactions:
-  - date: 
-    amount: 
-    description: 
-    account: 
-    offset_account: 
-  - date: 
-    description: 
-    transactions: 
-      - amount: 
-        account: 
-      - amount: 
-        account: 
+  - date:
+    amount:
+    description:
+    account:
+    offset_account:
+  - date:
+    description:
+    transactions:
+      - amount:
+        account:
+      - amount:
+        account:
 ```
 
 The ledger format schema is purposely lightweight. The only requirements are as follows:
-- the `account` field should be expressed in the following format: `account_classification:account_name`.
-- the `amount` field should be a number. It can include up to two (2) decimal points.  
-- the `date` field should be in the following format: `YYYY-MM-DD`. 
 
+- the `account` field should be expressed in the following format: `account_classification:account_name`.
+- the `amount` field should be a number. It can include up to two (2) decimal points.
+- the `date` field should be in the following format: `YYYY-MM-DD`.
diff --git a/src/cli.rs b/src/cli.rs
index 33885ff..b649928 100644
--- a/src/cli.rs
+++ b/src/cli.rs
@@ -1,82 +1,36 @@
 mod account;
+mod args;
 mod balance;
 mod csv;
 mod register;
-mod version;
 
-use crate::error::{Error, Result};
-use crate::model::ledger::Group;
-use pargs::Pargs;
-use std::env;
+extern crate clap;
 
-pub fn run() -> Result<()> {
-    let args: Vec<String> = env::args().collect();
-
-    // define expected args for pargs
-    let expected_command_args: Vec<String> = vec![
-        String::from("account"),
-        String::from("balance"),
-        String::from("register"),
-        String::from("csv"),
-        String::from("version"),
-    ];
-    let expected_flag_args: Vec<String> = vec![];
-    let expected_option_args: Vec<String> = vec![
-        String::from("-f"),
-        String::from("-o"),
-        String::from("-g"),
-        String::from("-s"),
-    ];
-
-    let Pargs {
-        command_args,
-        option_args,
-        ..
-    } = Pargs::parse(
-        args,
-        expected_command_args,
-        expected_flag_args,
-        expected_option_args,
-    )?;
-
-    let ledger_file_env = match std::env::var("RLEDGER_FILE") {
-        Ok(p) => p,
-        Err(err) => format!("{}", err),
-    };
-
-    let ledger_file = match option_args.get("-f") {
-        Some(value) => value.as_str(),
-        None => ledger_file_env.as_str(),
-    };
+use crate::error::Result;
+use args::{Args, Command};
 
-    let options_arg = match option_args.get("-o") {
-        Some(value) => String::from(value),
-        None => String::from(""),
-    };
-
-    let group_arg = match option_args.get("-g") {
-        Some(value) => match value.as_str() {
-            "month" => Group::Month,
-            "year" => Group::Year,
-            _ => panic!("that group command was not recognized."),
-        },
-        None => Group::None,
-    };
-
-    let offset_arg = match option_args.get("-s") {
-        Some(value) => String::from(value),
-        None => String::from(""),
-    };
-
-    match &command_args.len() {
-        0 => Err(Error::InvalidArg(String::from("please enter a command."))),
-        _ => match &command_args[0][..] {
-            "account" => account::account(ledger_file),
-            "balance" => balance::balance(ledger_file),
-            "register" => register::register(ledger_file, &options_arg, group_arg),
-            "csv" => csv::csv(ledger_file, &options_arg, &offset_arg),
-            "version" => version::version(),
-            _ => panic!("command not found."),
-        },
+pub fn run() -> Result<()> {
+    let mut matches = Args::new();
+    matches.populate_args();
+    let Args {
+        ledger_file,
+        options_arg,
+        offset_arg,
+        group_arg,
+        command,
+    } = matches;
+
+    match command {
+        Command::Account => account::account(ledger_file.as_str()),
+        Command::Balance => balance::balance(ledger_file.as_str()),
+        Command::Register => {
+            register::register(ledger_file.as_str(), options_arg.as_str(), group_arg)
+        }
+        Command::CSV => csv::csv(
+            ledger_file.as_str(),
+            options_arg.as_str(),
+            offset_arg.as_str(),
+        ),
+        Command::None => panic!("command not found"),
     }
 }
diff --git a/src/cli/args.rs b/src/cli/args.rs
new file mode 100644
index 0000000..85051cf
--- /dev/null
+++ b/src/cli/args.rs
@@ -0,0 +1,178 @@
+extern crate clap;
+use crate::model::ledger::Group;
+use clap::{crate_version, App, Arg, SubCommand};
+
+pub struct Args {
+    pub ledger_file: String,
+    pub options_arg: String,
+    pub group_arg: Group,
+    pub offset_arg: String,
+    pub command: Command,
+}
+
+pub enum Command {
+    Account,
+    Balance,
+    Register,
+    CSV,
+    None,
+}
+
+impl Args {
+    pub fn new() -> Args {
+        Args {
+            ledger_file: String::from(""),
+            options_arg: String::from(""),
+            group_arg: Group::None,
+            offset_arg: String::from(""),
+            command: Command::None,
+        }
+    }
+
+    pub fn populate_args(&mut self) {
+        let matches = App::new("rust_ledger")
+            .version(crate_version!())
+            .author("Eric Crowder <ebcrowder@gmail.com>")
+            .subcommand(
+                SubCommand::with_name("account")
+                    .about("account module")
+                    .arg(
+                        Arg::with_name("filename")
+                            .short("f")
+                            .long("filename")
+                            .help("location of ledger file")
+                            .takes_value(true),
+                    ),
+            )
+            .subcommand(
+                SubCommand::with_name("balance")
+                    .about("balance module")
+                    .arg(
+                        Arg::with_name("filename")
+                            .short("f")
+                            .long("filename")
+                            .help("location of ledger file")
+                            .takes_value(true),
+                    ),
+            )
+            .subcommand(
+                SubCommand::with_name("register")
+                    .about("register module")
+                    .arg(
+                        Arg::with_name("filename")
+                            .short("f")
+                            .long("filename")
+                            .help("location of ledger file")
+                            .takes_value(true),
+                    )
+                    .arg(
+                        Arg::with_name("option")
+                            .short("o")
+                            .long("option")
+                            .help("filter output by optional value")
+                            .takes_value(true),
+                    )
+                    .arg(
+                        Arg::with_name("group")
+                            .short("g")
+                            .long("group")
+                            .help("group register output by value")
+                            .takes_value(true),
+                    ),
+            )
+            .subcommand(
+                SubCommand::with_name("csv")
+                    .about("csv module")
+                    .arg(
+                        Arg::with_name("filename")
+                            .short("f")
+                            .long("filename")
+                            .help("location of ledger file")
+                            .takes_value(true),
+                    )
+                    .arg(
+                        Arg::with_name("csv")
+                            .short("c")
+                            .long("csv")
+                            .help("path of csv file")
+                            .takes_value(true),
+                    )
+                    .arg(
+                        Arg::with_name("offset")
+                            .short("o")
+                            .long("offset")
+                            .help("offset account for each csv transaction")
+                            .takes_value(true),
+                    ),
+            )
+            .get_matches();
+
+        if let Some(sub) = matches.subcommand_matches("register") {
+            self.ledger_file = match sub.value_of("filename") {
+                Some(f) => String::from(f),
+                None => match std::env::var("RLEDGER_FILE") {
+                    Ok(p) => p,
+                    Err(err) => format!("{}", err),
+                },
+            };
+            self.options_arg = match sub.value_of("option") {
+                Some(v) => String::from(v),
+                None => String::from(""),
+            };
+            self.group_arg = match sub.value_of("group") {
+                Some(v) => match v {
+                    "month" => Group::Month,
+                    "year" => Group::Year,
+                    _ => Group::None,
+                },
+                None => Group::None,
+            };
+        }
+
+        if let Some(sub) = matches.subcommand_matches("csv") {
+            self.ledger_file = match sub.value_of("filename") {
+                Some(f) => String::from(f),
+                None => match std::env::var("RLEDGER_FILE") {
+                    Ok(p) => p,
+                    Err(err) => format!("{}", err),
+                },
+            };
+            self.options_arg = match sub.value_of("csv") {
+                Some(v) => String::from(v),
+                None => String::from(""),
+            };
+            self.offset_arg = match sub.value_of("offset") {
+                Some(v) => String::from(v),
+                None => String::from(""),
+            };
+        }
+
+        if let Some(sub) = matches.subcommand_matches("account") {
+            self.ledger_file = match sub.value_of("filename") {
+                Some(f) => String::from(f),
+                None => match std::env::var("RLEDGER_FILE") {
+                    Ok(p) => p,
+                    Err(err) => format!("{}", err),
+                },
+            };
+        }
+
+        if let Some(sub) = matches.subcommand_matches("balance") {
+            self.ledger_file = match sub.value_of("filename") {
+                Some(f) => String::from(f),
+                None => match std::env::var("RLEDGER_FILE") {
+                    Ok(p) => p,
+                    Err(err) => format!("{}", err),
+                },
+            };
+        }
+
+        match matches.subcommand_name() {
+            Some("account") => self.command = Command::Account,
+            Some("balance") => self.command = Command::Balance,
+            Some("register") => self.command = Command::Register,
+            Some("csv") => self.command = Command::CSV,
+            _ => self.command = Command::None,
+        };
+    }
+}
diff --git a/src/cli/version.rs b/src/cli/version.rs
deleted file mode 100644
index ceaad58..0000000
--- a/src/cli/version.rs
+++ /dev/null
@@ -1,13 +0,0 @@
-use crate::error::Result;
-
-/// returns package version
-pub fn version() -> Result<()> {
-    let cargo_pkg_version = option_env!("CARGO_PKG_VERSION");
-
-    match cargo_pkg_version {
-        Some(v) => println!("rust_ledger {:?}", v),
-        None => println!("version not found in Cargo.toml"),
-    }
-
-    Ok(())
-}