diff --git a/.github/workflows/ruby.yml b/.github/workflows/ruby.yml
index 8eda42633..e96997e47 100644
--- a/.github/workflows/ruby.yml
+++ b/.github/workflows/ruby.yml
@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        ruby-version: ['2.6', '2.7']
+        ruby-version: ['3.0', '3.1', '3.2']
 
     steps:
     - uses: actions/checkout@v2
@@ -19,7 +19,10 @@ jobs:
       uses: ruby/setup-ruby@v1
       with:
         ruby-version: ${{ matrix.ruby-version }}
-        bundler-cache: true # runs 'bundle install' and caches installed gems automatically
+    - name: Set frozen config to false
+      run: bundle config set --local frozen false
+    - name: Install Dependencies
+      run: bundle install
     - name: Run tests
       run: bundle exec rake
     - name: Rubocop
diff --git a/.rubocop.yml b/.rubocop.yml
index 2751180fb..299df42e1 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -1,6 +1,6 @@
 inherit_from: .rubocop_todo.yml
 AllCops:
-  TargetRubyVersion: 2.4
+  TargetRubyVersion: 3.1.2
   Exclude:
     - 'test/**/*'
     - 'spec/**/*'
diff --git a/.rubocop_todo.yml b/.rubocop_todo.yml
index 0551bb8e5..ef845ac13 100644
--- a/.rubocop_todo.yml
+++ b/.rubocop_todo.yml
@@ -1,12 +1,20 @@
 # This configuration was generated by
 # `rubocop --auto-gen-config`
-# on 2021-03-30 16:14:38 -0400 using RuboCop version 0.80.0.
+# on 2023-11-17 19:45:05 UTC using RuboCop version 1.23.0.
 # The point is for the user to remove these configuration records
 # one by one as the offenses are removed from the code base.
 # Note that changes in the inspected code, or installation of new
 # versions of RuboCop, may require this file to be generated again.
 
-# Offense count: 51
+# Offense count: 1
+# Cop supports --auto-correct.
+# Configuration parameters: EnforcedStyleAlignWith, Severity.
+# SupportedStylesAlignWith: start_of_line, begin
+Layout/BeginEndAlignment:
+  Exclude:
+    - 'lib/fhir_models/bootstrap/model.rb'
+
+# Offense count: 49
 # Cop supports --auto-correct.
 Layout/EmptyLineAfterGuardClause:
   Exclude:
@@ -26,22 +34,22 @@ Layout/EmptyLineAfterGuardClause:
 # Cop supports --auto-correct.
 Layout/RescueEnsureAlignment:
   Exclude:
-    - 'lib/fhir_models/bootstrap/hashable.rb'
+    - 'lib/fhir_models/bootstrap/model.rb'
 
-# Offense count: 2
+# Offense count: 1
 # Cop supports --auto-correct.
 Lint/ToJSON:
   Exclude:
-    - 'lib/fhir_models/bootstrap/json.rb'
     - 'lib/fhir_models/fhir_ext/structure_definition_finding.rb'
 
-# Offense count: 40
+# Offense count: 38
+# Configuration parameters: IgnoredMethods, CountRepeatedAttributes.
 Metrics/AbcSize:
-  Max: 392
+  Max: 394
 
 # Offense count: 7
-# Configuration parameters: CountComments, ExcludedMethods.
-# ExcludedMethods: refine
+# Configuration parameters: CountComments, CountAsOne, ExcludedMethods, IgnoredMethods.
+# IgnoredMethods: refine
 Metrics/BlockLength:
   Max: 78
 
@@ -51,31 +59,40 @@ Metrics/BlockNesting:
   Max: 5
 
 # Offense count: 7
-# Configuration parameters: CountComments.
+# Configuration parameters: CountComments, CountAsOne.
 Metrics/ClassLength:
-  Max: 356
+  Max: 355
 
-# Offense count: 23
+# Offense count: 32
+# Configuration parameters: IgnoredMethods.
 Metrics/CyclomaticComplexity:
-  Max: 65
+  Max: 73
 
-# Offense count: 44
-# Configuration parameters: CountComments, ExcludedMethods.
+# Offense count: 45
+# Configuration parameters: CountComments, CountAsOne, ExcludedMethods, IgnoredMethods.
 Metrics/MethodLength:
-  Max: 133
+  Max: 132
 
 # Offense count: 2
-# Configuration parameters: CountComments.
+# Configuration parameters: CountComments, CountAsOne.
 Metrics/ModuleLength:
   Max: 114
 
-# Offense count: 23
+# Offense count: 28
+# Configuration parameters: IgnoredMethods.
 Metrics/PerceivedComplexity:
-  Max: 68
+  Max: 76
+
+# Offense count: 5
+# Configuration parameters: EnforcedStyle, IgnoredPatterns.
+# SupportedStyles: snake_case, camelCase
+Naming/MethodName:
+  Exclude:
+    - 'lib/fhir_models/fhir_ext/structure_definition_finding.rb'
 
 # Offense count: 4
 # Configuration parameters: MinNameLength, AllowNamesEndingInNumbers, AllowedNames, ForbiddenNames.
-# AllowedNames: io, id, to, by, on, in, at, ip, db, os, pp
+# AllowedNames: at, by, db, id, in, io, ip, of, on, os, pp, to
 Naming/MethodParameterName:
   Exclude:
     - 'lib/fhir_models/fhir_ext/structure_definition_compare.rb'
@@ -87,11 +104,36 @@ Naming/RescuedExceptionsVariableName:
   Exclude:
     - 'lib/fhir_models/bootstrap/hashable.rb'
 
+# Offense count: 35
+# Cop supports --auto-correct.
+# Configuration parameters: EnforcedStyle.
+# SupportedStyles: separated, grouped
+Style/AccessorGrouping:
+  Exclude:
+    - 'lib/fhir_models/bootstrap/field.rb'
+    - 'lib/fhir_models/bootstrap/generator.rb'
+    - 'lib/fhir_models/bootstrap/template.rb'
+    - 'lib/fhir_models/fhir_ext/element_definition.rb'
+    - 'lib/fhir_models/fhir_ext/structure_definition.rb'
+    - 'lib/fhir_models/fhir_ext/structure_definition_finding.rb'
+
+# Offense count: 5
+# Cop supports --auto-correct.
+Style/CaseLikeIf:
+  Exclude:
+    - 'lib/fhir_models/bootstrap/hashable.rb'
+    - 'lib/fhir_models/bootstrap/model.rb'
+    - 'lib/fhir_models/bootstrap/preprocess.rb'
+    - 'lib/fhir_models/bootstrap/xml.rb'
+    - 'lib/fhir_models/fhir_ext/structure_definition.rb'
+
 # Offense count: 1
-# Configuration parameters: .
-# SupportedStyles: inline, group
-Style/AccessModifierDeclarations:
-  EnforcedStyle: inline
+# Cop supports --auto-correct.
+# Configuration parameters: EnforcedStyle.
+# SupportedStyles: nested, compact
+Style/ClassAndModuleChildren:
+  Exclude:
+    - '.simplecov'
 
 # Offense count: 17
 Style/ClassVars:
@@ -99,17 +141,31 @@ Style/ClassVars:
     - 'lib/fhir_models/bootstrap/definitions.rb'
     - 'lib/fhir_models/fhirpath/parse.rb'
 
+# Offense count: 1
+Style/CombinableLoops:
+  Exclude:
+    - 'lib/fhir_models/fhir_ext/structure_definition_compare.rb'
+
+# Offense count: 1
+# Cop supports --auto-correct.
+# Configuration parameters: Keywords, RequireColon.
+# Keywords: TODO, FIXME, OPTIMIZE, HACK, REVIEW, NOTE
+Style/CommentAnnotation:
+  Exclude:
+    - 'Guardfile'
+
 # Offense count: 6
+# Cop supports --auto-correct.
 Style/CommentedKeyword:
   Exclude:
     - 'lib/fhir_models/bootstrap/hashable.rb'
     - 'lib/fhir_models/bootstrap/model.rb'
 
-# Offense count: 14
+# Offense count: 15
+# Configuration parameters: AllowedConstants.
 Style/Documentation:
   Exclude:
-    - 'spec/**/*'
-    - 'test/**/*'
+    - '.simplecov'
     - 'lib/fhir_models/bootstrap/definitions.rb'
     - 'lib/fhir_models/bootstrap/field.rb'
     - 'lib/fhir_models/bootstrap/generator.rb'
@@ -125,6 +181,12 @@ Style/Documentation:
     - 'lib/fhir_models/fhirpath/expression.rb'
     - 'lib/fhir_models/fhirpath/parse.rb'
 
+# Offense count: 1
+# Cop supports --auto-correct.
+Style/GlobalStdStream:
+  Exclude:
+    - 'lib/fhir_models/fhir.rb'
+
 # Offense count: 28
 # Cop supports --auto-correct.
 Style/IfUnlessModifier:
@@ -136,39 +198,71 @@ Style/IfUnlessModifier:
     - 'lib/fhir_models/fhir_ext/structure_definition.rb'
     - 'lib/fhir_models/fhir_ext/structure_definition_compare.rb'
 
-# Offense count: 1
-Style/MethodMissingSuper:
-  Exclude:
-    - 'lib/fhir_models/bootstrap/model.rb'
-
 # Offense count: 1
 Style/MissingRespondToMissing:
   Exclude:
     - 'lib/fhir_models/bootstrap/model.rb'
 
-# Offense count: 9
+# Offense count: 6
+# Cop supports --auto-correct.
+# Configuration parameters: AllowMethodComparison.
 Style/MultipleComparison:
   Exclude:
-    - 'lib/fhir_models/bootstrap/definitions.rb'
     - 'lib/fhir_models/bootstrap/generator.rb'
     - 'lib/fhir_models/bootstrap/model.rb'
     - 'lib/fhir_models/fhir_ext/structure_definition.rb'
 
 # Offense count: 2
 # Cop supports --auto-correct.
-# Configuration parameters: AutoCorrect, EnforcedStyle, IgnoredMethods.
+# Configuration parameters: EnforcedStyle, IgnoredMethods.
 # SupportedStyles: predicate, comparison
 Style/NumericPredicate:
   Exclude:
-    - 'spec/**/*'
     - 'lib/fhir_models/fhir_ext/structure_definition_compare.rb'
 
+# Offense count: 2
+# Configuration parameters: AllowedMethods.
+# AllowedMethods: respond_to_missing?
+Style/OptionalBooleanParameter:
+  Exclude:
+    - 'lib/fhir_models/bootstrap/generator.rb'
+    - 'lib/fhir_models/bootstrap/template.rb'
+
 # Offense count: 1
 # Cop supports --auto-correct.
 Style/OrAssignment:
   Exclude:
     - 'lib/fhir_models/bootstrap/generator.rb'
 
+# Offense count: 2
+# Cop supports --auto-correct.
+Style/RedundantBegin:
+  Exclude:
+    - 'lib/fhir_models/fhir_ext/structure_definition.rb'
+    - 'lib/fhir_models/fhirpath/expression.rb'
+
+# Offense count: 2
+# Cop supports --auto-correct.
+Style/RedundantRegexpCharacterClass:
+  Exclude:
+    - 'lib/fhir_models/fhir.rb'
+
+# Offense count: 6
+# Cop supports --auto-correct.
+Style/RedundantRegexpEscape:
+  Exclude:
+    - 'lib/fhir_models/bootstrap/generator.rb'
+    - 'lib/fhir_models/bootstrap/model.rb'
+    - 'lib/fhir_models/bootstrap/preprocess.rb'
+    - 'lib/fhir_models/fhir.rb'
+    - 'lib/fhir_models/fhirpath/parse.rb'
+
+# Offense count: 1
+# Cop supports --auto-correct.
+Style/RedundantSelfAssignment:
+  Exclude:
+    - 'lib/fhir_models/fhir_ext/element_definition.rb'
+
 # Offense count: 16
 # Cop supports --auto-correct.
 # Configuration parameters: EnforcedStyle.
@@ -196,6 +290,31 @@ Style/SafeNavigation:
     - 'lib/fhir_models/bootstrap/xml.rb'
     - 'lib/fhir_models/fhir_ext/structure_definition.rb'
 
+# Offense count: 9
+# Cop supports --auto-correct.
+Style/SlicingWithRange:
+  Exclude:
+    - 'lib/fhir_models/bootstrap/field.rb'
+    - 'lib/fhir_models/bootstrap/generator.rb'
+    - 'lib/fhir_models/bootstrap/model.rb'
+    - 'lib/fhir_models/fhir_ext/structure_definition.rb'
+    - 'lib/fhir_models/fhirpath/parse.rb'
+
+# Offense count: 1
+# Cop supports --auto-correct.
+# Configuration parameters: AllowModifier.
+Style/SoleNestedConditional:
+  Exclude:
+    - 'lib/fhir_models/fhir_ext/structure_definition_compare.rb'
+
+# Offense count: 2
+# Cop supports --auto-correct.
+# Configuration parameters: EnforcedStyle, ConsistentQuotesInMultiline.
+# SupportedStyles: single_quotes, double_quotes
+Style/StringLiterals:
+  Exclude:
+    - '.simplecov'
+
 # Offense count: 7
 # Cop supports --auto-correct.
 # Configuration parameters: EnforcedStyle.
diff --git a/.simplecov b/.simplecov
index a555a3758..bdf3dbbb9 100644
--- a/.simplecov
+++ b/.simplecov
@@ -1,9 +1,9 @@
 require 'simplecov'
 SimpleCov.command_name 'Unit Tests'
-SimpleCov.start do
-  add_filter "test/"
-  add_group "Library", "lib"
-end
+# SimpleCov.start do
+#   add_filter "test/"
+#   add_group "Library", "lib"
+# end
 
 class SimpleCov::Formatter::QualityFormatter
   def format(result)
diff --git a/Gemfile.lock b/Gemfile.lock
index e4f86e1d3..764904c3f 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -14,21 +14,21 @@ GEM
     bcp47 (0.3.3)
       i18n
     coderay (1.1.3)
-    concurrent-ruby (1.1.10)
+    concurrent-ruby (1.2.2)
     coolline (0.5.0)
       unicode_utils (~> 1.4)
     date_time_precision (0.8.1)
-    diff-lcs (1.4.4)
-    docile (1.3.2)
-    ffi (1.13.1)
-    formatador (0.2.5)
-    guard (2.16.2)
+    diff-lcs (1.5.0)
+    docile (1.4.0)
+    ffi (1.16.3)
+    formatador (1.1.0)
+    guard (2.18.1)
       formatador (>= 0.2.4)
       listen (>= 2.7, < 4.0)
       lumberjack (>= 1.0.12, < 2.0)
       nenv (~> 0.1)
       notiffany (~> 0.0)
-      pry (>= 0.9.12)
+      pry (>= 0.13.0)
       shellany (~> 0.0)
       thor (>= 0.18.1)
     guard-compat (1.2.1)
@@ -39,22 +39,19 @@ GEM
     guard-test (2.0.8)
       guard-compat (~> 1.2)
       test-unit (~> 3.0)
-    i18n (1.12.0)
+    i18n (1.14.1)
       concurrent-ruby (~> 1.0)
-    jaro_winkler (1.5.4)
-    json (2.3.1)
-    listen (3.3.1)
+    json (2.6.3)
+    listen (3.8.0)
       rb-fsevent (~> 0.10, >= 0.10.3)
       rb-inotify (~> 0.9, >= 0.9.10)
-    lumberjack (1.2.8)
+    lumberjack (1.2.10)
     method_source (1.0.0)
-    mime-types (3.4.1)
+    mime-types (3.5.1)
       mime-types-data (~> 3.2015)
-    mime-types-data (3.2022.0105)
-    mini_portile2 (2.5.3)
+    mime-types-data (3.2023.1003)
     nenv (0.3.0)
-    nokogiri (1.11.7)
-      mini_portile2 (~> 2.5.0)
+    nokogiri (1.15.5-x86_64-linux)
       racc (~> 1.4)
     nokogiri-diff (0.2.0)
       nokogiri (~> 1.5)
@@ -62,44 +59,50 @@ GEM
     notiffany (0.1.3)
       nenv (~> 0.1)
       shellany (~> 0.0)
-    parallel (1.20.1)
-    parser (3.0.0.0)
+    parallel (1.23.0)
+    parser (3.2.2.4)
       ast (~> 2.4.1)
-    power_assert (1.2.0)
-    pry (0.13.1)
+      racc
+    power_assert (2.0.3)
+    pry (0.14.2)
       coderay (~> 1.1)
       method_source (~> 1.0)
-    pry-coolline (0.2.5)
+    pry-coolline (0.2.6)
       coolline (~> 0.5)
-    racc (1.5.2)
-    rainbow (3.0.0)
-    rake (13.0.1)
-    rb-fsevent (0.10.4)
+      pry (~> 0.13)
+    racc (1.7.3)
+    rainbow (3.1.1)
+    rake (13.1.0)
+    rb-fsevent (0.11.2)
     rb-inotify (0.10.1)
       ffi (~> 1.0)
-    rexml (3.2.5)
-    rspec (3.10.0)
-      rspec-core (~> 3.10.0)
-      rspec-expectations (~> 3.10.0)
-      rspec-mocks (~> 3.10.0)
-    rspec-core (3.10.0)
-      rspec-support (~> 3.10.0)
-    rspec-expectations (3.10.0)
+    regexp_parser (2.8.2)
+    rexml (3.2.6)
+    rspec (3.12.0)
+      rspec-core (~> 3.12.0)
+      rspec-expectations (~> 3.12.0)
+      rspec-mocks (~> 3.12.0)
+    rspec-core (3.12.2)
+      rspec-support (~> 3.12.0)
+    rspec-expectations (3.12.3)
       diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.10.0)
-    rspec-mocks (3.10.0)
+      rspec-support (~> 3.12.0)
+    rspec-mocks (3.12.6)
       diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.10.0)
-    rspec-support (3.10.0)
-    rubocop (0.80.0)
-      jaro_winkler (~> 1.5.1)
+      rspec-support (~> 3.12.0)
+    rspec-support (3.12.1)
+    rubocop (1.23.0)
       parallel (~> 1.10)
-      parser (>= 2.7.0.1)
+      parser (>= 3.0.0.0)
       rainbow (>= 2.2.2, < 4.0)
+      regexp_parser (>= 1.8, < 3.0)
       rexml
+      rubocop-ast (>= 1.12.0, < 2.0)
       ruby-progressbar (~> 1.7)
-      unicode-display_width (>= 1.4.0, < 1.7)
-    ruby-progressbar (1.11.0)
+      unicode-display_width (>= 1.4.0, < 3.0)
+    rubocop-ast (1.30.0)
+      parser (>= 3.2.1.0)
+    ruby-progressbar (1.13.0)
     shellany (0.0.1)
     simplecov (0.17.1)
       docile (~> 1.1)
@@ -107,14 +110,14 @@ GEM
       simplecov-html (~> 0.10.0)
     simplecov-html (0.10.2)
     tdiff (0.3.4)
-    test-unit (3.3.6)
+    test-unit (3.6.1)
       power_assert
-    thor (1.0.1)
-    unicode-display_width (1.6.1)
+    thor (1.3.0)
+    unicode-display_width (2.5.0)
     unicode_utils (1.4.0)
 
 PLATFORMS
-  ruby
+  x86_64-linux
 
 DEPENDENCIES
   bundler
@@ -126,12 +129,12 @@ DEPENDENCIES
   pry-coolline
   rake
   rspec
-  rubocop (= 0.80)
+  rubocop (= 1.23.0)
   simplecov (~> 0.17.0)
   test-unit
 
 RUBY VERSION
-   ruby 2.7.4p191
+   ruby 3.1.2p20
 
 BUNDLED WITH
-   2.2.21
+   2.4.17
diff --git a/fhir_models.gemspec b/fhir_models.gemspec
index fac646552..803142387 100644
--- a/fhir_models.gemspec
+++ b/fhir_models.gemspec
@@ -34,7 +34,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency 'rspec'
   spec.add_development_dependency 'simplecov', '~> 0.17.0'
   spec.add_development_dependency 'nokogiri-diff'
-  spec.add_development_dependency 'rubocop', '0.80'
+  spec.add_development_dependency 'rubocop', '1.23.0'
   spec.add_development_dependency 'guard-rspec'
   spec.add_development_dependency 'guard-test'
 end