diff --git a/web/templates/concepts.html b/web/templates/concepts.html
index 49e8c0249..62923ffd8 100644
--- a/web/templates/concepts.html
+++ b/web/templates/concepts.html
@@ -23,6 +23,17 @@ <h1 class="col-12">{{ title }}</h1>
                     the language column{{ languages | length | pluralize }} to correct any
                     information.
                 </p>
+                {% for lang in languages %}
+                    {% if lang.is_incomplete %}
+                    <div class="alert alert-link" role="alert">
+                        {{ lang.name }} ({{ lang.version }})'s thesaurus is incomplete. Please help us improve by
+                        <a href="https://github.com/codethesaurus/codethesaur.us/edit/main/web/thesauruses/{{ lang.key }}/{{ lang.version }}/{{ concept }}.json" rel="noopener">
+                            adding or correcting information
+                        </a>
+                        for this language.
+                    </div>
+                    {% endif %}
+                {% endfor %}
             </div>
 
 {% for category in categories %}
diff --git a/web/views.py b/web/views.py
index cad8c61e1..ff9e19b48 100644
--- a/web/views.py
+++ b/web/views.py
@@ -191,10 +191,31 @@ def concepts(request):
     for (category_key, category) in meta_structure.categories.items():
         concepts_list = [concepts_data(key, name, languages) for (key, name) in category.items()]
 
-        all_categories.append({
+        category_entry = {
             "key": category_key,
-            "concepts": concepts_list
-        })
+            "concepts": concepts_list,
+            "is_incomplete": [False] * len(languages)
+        }
+        for i in range(len(languages)):
+            is_incomplete = True
+            for concept in concepts_list:
+                if not languages[i].concept_unknown(concept["key"]) and \
+                    languages[i].concept_implemented(concept["key"]):
+                    is_incomplete = False
+                if languages[i].concept_unknown(concept["key"]) or \
+                    (languages[i].concept_implemented(concept["key"]) and \
+                    not languages[i].concept_code(concept["key"]) and \
+                    not languages[i].concept_comment(concept["key"]) ):
+                    category_entry["is_incomplete"][i] = True
+                    break
+            if is_incomplete:
+                category_entry["is_incomplete"][i] = True
+        all_categories.append(category_entry)
+
+    for lang in languages:
+        booleans = [category["is_incomplete"][languages.index(lang)] for category in all_categories]
+        lang._is_incomplete = any(booleans)
+
     return render_concepts(request, languages, meta_structure, all_categories)
 
 
@@ -217,7 +238,8 @@ def render_concepts(request, languages, structure, all_categories):
             {
                 "key": language.key,
                 "version": language.version,
-                "name": language.name
+                "name": language.name,
+                "is_incomplete": language._is_incomplete,
             }
             for language in languages
         ],