diff --git a/src/commit/types/message.rs b/src/commit/types/message.rs
new file mode 100644
index 0000000..d7ab00f
--- /dev/null
+++ b/src/commit/types/message.rs
@@ -0,0 +1,509 @@
+use super::{CommitType, Description, Scope};
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct ConventionalCommit {
+    commit_type: CommitType,
+    scope: Scope,
+    description: Description,
+}
+
+impl ConventionalCommit {
+    /// Create a new conventional commit message
+    ///
+    /// # Arguments
+    /// All arguments are pre-validated types, so this cannot fail
+    pub fn new(commit_type: CommitType, scope: Scope, description: Description) -> Self {
+        Self {
+            commit_type,
+            scope,
+            description,
+        }
+    }
+
+    /// Format the complete commit messsage
+    ///
+    /// Returns `type(scope): description` if scope is non-empty, or
+    /// `type: description` if scope is empty
+    pub fn format(&self) -> String {
+        if self.scope.is_empty() {
+            format!("{}: {}", self.commit_type, self.description)
+        } else {
+            format!("{}({}): {}", self.commit_type, self.scope, self.description)
+        }
+    }
+
+    /// Returns the commit type
+    pub fn commit_type(&self) -> CommitType {
+        self.commit_type
+    }
+
+    /// Returns a reference to the scope
+    pub fn scope(&self) -> &Scope {
+        &self.scope
+    }
+
+    /// Returns a reference to the description
+    pub fn description(&self) -> &Description {
+        &self.description
+    }
+}
+
+impl std::fmt::Display for ConventionalCommit {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}", self.format())
+    }
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /// Helper to create a valid Scope for testing
+    fn test_scope(value: &str) -> Scope {
+        Scope::parse(value).expect("test scope should be valid")
+    }
+
+    /// Helper to create a valid Description for testing
+    fn test_description(value: &str) -> Description {
+        Description::parse(value).expect("test description should be valid")
+    }
+
+    /// Test that ConventionalCommit::new() creates a valid commit with all fields
+    #[test]
+    fn new_creates_commit_with_all_fields() {
+        let commit = ConventionalCommit::new(
+            CommitType::Feat,
+            test_scope("cli"),
+            test_description("add new feature"),
+        );
+        assert_eq!(commit.commit_type(), CommitType::Feat);
+        assert_eq!(commit.scope().as_str(), "cli");
+        assert_eq!(commit.description().as_str(), "add new feature");
+    }
+
+    /// Test that ConventionalCommit::new() works with empty scope
+    #[test]
+    fn new_creates_commit_with_empty_scope() {
+        let commit = ConventionalCommit::new(
+            CommitType::Fix,
+            Scope::empty(),
+            test_description("fix critical bug"),
+        );
+        assert_eq!(commit.commit_type(), CommitType::Fix);
+        assert!(commit.scope().is_empty());
+        assert_eq!(commit.description().as_str(), "fix critical bug");
+    }
+
+    /// Test that format() produces "type(scope): description" when scope is non-empty
+    #[test]
+    fn format_with_scope_produces_correct_output() {
+        let commit = ConventionalCommit::new(
+            CommitType::Feat,
+            test_scope("auth"),
+            test_description("add login"),
+        );
+        assert_eq!(commit.format(), "feat(auth): add login");
+    }
+
+    /// Test format with different scope values
+    #[test]
+    fn format_with_various_scopes() {
+        // Hyphenated scope
+        let commit1 = ConventionalCommit::new(
+            CommitType::Fix,
+            test_scope("user-auth"),
+            test_description("fix token refresh"),
+        );
+        assert_eq!(commit1.format(), "fix(user-auth): fix token refresh");
+
+        // Underscored scope
+        let commit2 = ConventionalCommit::new(
+            CommitType::Docs,
+            test_scope("api_docs"),
+            test_description("update README"),
+        );
+        assert_eq!(commit2.format(), "docs(api_docs): update README");
+
+        // Scope with slash (Jira-style)
+        let commit3 = ConventionalCommit::new(
+            CommitType::Chore,
+            test_scope("PROJ-123/cleanup"),
+            test_description("remove unused code"),
+        );
+        assert_eq!(
+            commit3.format(),
+            "chore(PROJ-123/cleanup): remove unused code"
+        );
+    }
+
+    /// Test that format() produces "type: description" when scope is empty
+    #[test]
+    fn format_without_scope_produces_correct_output() {
+        let commit = ConventionalCommit::new(
+            CommitType::Feat,
+            Scope::empty(),
+            test_description("add login"),
+        );
+        assert_eq!(commit.format(), "feat: add login");
+    }
+
+    /// Test format without scope for various descriptions
+    #[test]
+    fn format_without_scope_various_descriptions() {
+        let commit1 = ConventionalCommit::new(
+            CommitType::Fix,
+            Scope::empty(),
+            test_description("fix critical bug"),
+        );
+        assert_eq!(commit1.format(), "fix: fix critical bug");
+
+        let commit2 = ConventionalCommit::new(
+            CommitType::Docs,
+            Scope::empty(),
+            test_description("update installation guide"),
+        );
+        assert_eq!(commit2.format(), "docs: update installation guide");
+    }
+
+    /// Test that all 11 commit types format correctly with scope
+    #[test]
+    fn all_commit_types_format_correctly_with_scope() {
+        let scope = test_scope("cli");
+        let desc = test_description("test change");
+
+        let expected_formats = [
+            (CommitType::Feat, "feat(cli): test change"),
+            (CommitType::Fix, "fix(cli): test change"),
+            (CommitType::Docs, "docs(cli): test change"),
+            (CommitType::Style, "style(cli): test change"),
+            (CommitType::Refactor, "refactor(cli): test change"),
+            (CommitType::Perf, "perf(cli): test change"),
+            (CommitType::Test, "test(cli): test change"),
+            (CommitType::Build, "build(cli): test change"),
+            (CommitType::Ci, "ci(cli): test change"),
+            (CommitType::Chore, "chore(cli): test change"),
+            (CommitType::Revert, "revert(cli): test change"),
+        ];
+
+        for (commit_type, expected) in expected_formats {
+            let commit = ConventionalCommit::new(commit_type, scope.clone(), desc.clone());
+            assert_eq!(
+                commit.format(),
+                expected,
+                "Format should be correct for {:?}",
+                commit_type
+            );
+        }
+    }
+
+    /// Test that all 11 commit types format correctly without scope
+    #[test]
+    fn all_commit_types_format_correctly_without_scope() {
+        let desc = test_description("test change");
+
+        let expected_formats = [
+            (CommitType::Feat, "feat: test change"),
+            (CommitType::Fix, "fix: test change"),
+            (CommitType::Docs, "docs: test change"),
+            (CommitType::Style, "style: test change"),
+            (CommitType::Refactor, "refactor: test change"),
+            (CommitType::Perf, "perf: test change"),
+            (CommitType::Test, "test: test change"),
+            (CommitType::Build, "build: test change"),
+            (CommitType::Ci, "ci: test change"),
+            (CommitType::Chore, "chore: test change"),
+            (CommitType::Revert, "revert: test change"),
+        ];
+
+        for (commit_type, expected) in expected_formats {
+            let commit = ConventionalCommit::new(commit_type, Scope::empty(), desc.clone());
+            assert_eq!(
+                commit.format(),
+                expected,
+                "Format should be correct for {:?}",
+                commit_type
+            );
+        }
+    }
+
+    /// Test that Display implementation delegates to format()
+    #[test]
+    fn display_delegates_to_format() {
+        let commit = ConventionalCommit::new(
+            CommitType::Feat,
+            test_scope("auth"),
+            test_description("add login"),
+        );
+        let display_output = format!("{}", commit);
+        let format_output = commit.format();
+        assert_eq!(display_output, format_output);
+    }
+
+    /// Test Display with scope
+    #[test]
+    fn display_with_scope() {
+        let commit = ConventionalCommit::new(
+            CommitType::Fix,
+            test_scope("api"),
+            test_description("handle null response"),
+        );
+        assert_eq!(format!("{}", commit), "fix(api): handle null response");
+    }
+
+    /// Test Display without scope
+    #[test]
+    fn display_without_scope() {
+        let commit = ConventionalCommit::new(
+            CommitType::Docs,
+            Scope::empty(),
+            test_description("improve README"),
+        );
+        assert_eq!(format!("{}", commit), "docs: improve README");
+    }
+
+    /// Test Display delegates to format for all commit types
+    #[test]
+    fn display_equals_format_for_all_types() {
+        for commit_type in CommitType::all() {
+            // With scope
+            let commit_with_scope = ConventionalCommit::new(
+                *commit_type,
+                test_scope("test"),
+                test_description("change"),
+            );
+            assert_eq!(
+                format!("{}", commit_with_scope),
+                commit_with_scope.format(),
+                "Display should equal format() for {:?} with scope",
+                commit_type
+            );
+
+            // Without scope
+            let commit_without_scope =
+                ConventionalCommit::new(*commit_type, Scope::empty(), test_description("change"));
+            assert_eq!(
+                format!("{}", commit_without_scope),
+                commit_without_scope.format(),
+                "Display should equal format() for {:?} without scope",
+                commit_type
+            );
+        }
+    }
+
+    /// Test commit_type() returns the correct type
+    #[test]
+    fn commit_type_accessor_returns_correct_type() {
+        for commit_type in CommitType::all() {
+            let commit =
+                ConventionalCommit::new(*commit_type, Scope::empty(), test_description("test"));
+            assert_eq!(commit.commit_type(), *commit_type);
+        }
+    }
+
+    /// Test scope() returns reference to scope
+    #[test]
+    fn scope_accessor_returns_reference() {
+        let commit = ConventionalCommit::new(
+            CommitType::Feat,
+            test_scope("auth"),
+            test_description("add feature"),
+        );
+        assert_eq!(commit.scope().as_str(), "auth");
+    }
+
+    /// Test scope() returns reference to empty scope
+    #[test]
+    fn scope_accessor_returns_empty_scope() {
+        let commit = ConventionalCommit::new(
+            CommitType::Feat,
+            Scope::empty(),
+            test_description("add feature"),
+        );
+        assert!(commit.scope().is_empty());
+    }
+
+    /// Test description() returns reference to description
+    #[test]
+    fn description_accessor_returns_reference() {
+        let commit = ConventionalCommit::new(
+            CommitType::Feat,
+            Scope::empty(),
+            test_description("add new authentication flow"),
+        );
+        assert_eq!(commit.description().as_str(), "add new authentication flow");
+    }
+
+    /// Test Clone trait
+    #[test]
+    fn conventional_commit_is_cloneable() {
+        let original = ConventionalCommit::new(
+            CommitType::Feat,
+            test_scope("cli"),
+            test_description("add feature"),
+        );
+        let cloned = original.clone();
+        assert_eq!(original, cloned);
+    }
+
+    /// Test PartialEq trait - equal commits
+    #[test]
+    fn conventional_commit_equality() {
+        let commit1 = ConventionalCommit::new(
+            CommitType::Feat,
+            test_scope("cli"),
+            test_description("add feature"),
+        );
+        let commit2 = ConventionalCommit::new(
+            CommitType::Feat,
+            test_scope("cli"),
+            test_description("add feature"),
+        );
+        assert_eq!(commit1, commit2);
+    }
+
+    /// Test PartialEq trait - different commit types
+    #[test]
+    fn conventional_commit_inequality_different_type() {
+        let commit1 = ConventionalCommit::new(
+            CommitType::Feat,
+            test_scope("cli"),
+            test_description("change"),
+        );
+        let commit2 = ConventionalCommit::new(
+            CommitType::Fix,
+            test_scope("cli"),
+            test_description("change"),
+        );
+        assert_ne!(commit1, commit2);
+    }
+
+    /// Test PartialEq trait - different scopes
+    #[test]
+    fn conventional_commit_inequality_different_scope() {
+        let commit1 = ConventionalCommit::new(
+            CommitType::Feat,
+            test_scope("cli"),
+            test_description("change"),
+        );
+        let commit2 = ConventionalCommit::new(
+            CommitType::Feat,
+            test_scope("api"),
+            test_description("change"),
+        );
+        assert_ne!(commit1, commit2);
+    }
+
+    /// Test PartialEq trait - different descriptions
+    #[test]
+    fn conventional_commit_inequality_different_description() {
+        let commit1 = ConventionalCommit::new(
+            CommitType::Feat,
+            test_scope("cli"),
+            test_description("add feature"),
+        );
+        let commit2 = ConventionalCommit::new(
+            CommitType::Feat,
+            test_scope("cli"),
+            test_description("fix bug"),
+        );
+        assert_ne!(commit1, commit2);
+    }
+
+    /// Test Debug trait
+    #[test]
+    fn conventional_commit_has_debug() {
+        let commit = ConventionalCommit::new(
+            CommitType::Feat,
+            test_scope("cli"),
+            test_description("add feature"),
+        );
+        let debug_output = format!("{:?}", commit);
+        assert!(debug_output.contains("ConventionalCommit"));
+        assert!(debug_output.contains("Feat"));
+    }
+
+    /// Test real-world commit message example: feature with scope
+    #[test]
+    fn real_world_feature_with_scope() {
+        let commit = ConventionalCommit::new(
+            CommitType::Feat,
+            test_scope("auth"),
+            test_description("implement OAuth2 login flow"),
+        );
+        assert_eq!(commit.format(), "feat(auth): implement OAuth2 login flow");
+    }
+
+    /// Test real-world commit message example: bug fix without scope
+    #[test]
+    fn real_world_bugfix_without_scope() {
+        let commit = ConventionalCommit::new(
+            CommitType::Fix,
+            Scope::empty(),
+            test_description("prevent crash on empty input"),
+        );
+        assert_eq!(commit.format(), "fix: prevent crash on empty input");
+    }
+
+    /// Test real-world commit message example: documentation
+    #[test]
+    fn real_world_docs() {
+        let commit = ConventionalCommit::new(
+            CommitType::Docs,
+            test_scope("README"),
+            test_description("add installation instructions"),
+        );
+        assert_eq!(
+            commit.format(),
+            "docs(README): add installation instructions"
+        );
+    }
+
+    /// Test real-world commit message example: refactoring
+    #[test]
+    fn real_world_refactor() {
+        let commit = ConventionalCommit::new(
+            CommitType::Refactor,
+            test_scope("core"),
+            test_description("extract validation logic"),
+        );
+        assert_eq!(commit.format(), "refactor(core): extract validation logic");
+    }
+
+    /// Test real-world commit message example: CI change
+    #[test]
+    fn real_world_ci() {
+        let commit = ConventionalCommit::new(
+            CommitType::Ci,
+            test_scope("github"),
+            test_description("add release workflow"),
+        );
+        assert_eq!(commit.format(), "ci(github): add release workflow");
+    }
+
+    /// Test commit message with maximum length description (72 chars)
+    #[test]
+    fn format_with_max_length_description() {
+        let long_desc = "a".repeat(72);
+        let commit = ConventionalCommit::new(
+            CommitType::Feat,
+            Scope::empty(),
+            Description::parse(&long_desc).unwrap(),
+        );
+        // Format should be "feat: " + 72 chars = 78 total chars
+        let formatted = commit.format();
+        assert!(formatted.starts_with("feat: "));
+        assert_eq!(formatted.len(), 78); // "feat: " (6) + 72 = 78
+    }
+
+    /// Test commit message with scope containing all valid special chars
+    #[test]
+    fn format_with_complex_scope() {
+        let commit = ConventionalCommit::new(
+            CommitType::Feat,
+            test_scope("my-scope_v2/feature"),
+            test_description("add support"),
+        );
+        assert_eq!(commit.format(), "feat(my-scope_v2/feature): add support");
+    }
+}
diff --git a/src/commit/types/mod.rs b/src/commit/types/mod.rs
index e4e0973..5424949 100644
--- a/src/commit/types/mod.rs
+++ b/src/commit/types/mod.rs
@@ -6,3 +6,5 @@ pub use scope::{Scope, ScopeError};
 
 mod description;
 pub use description::{Description, DescriptionError};
+
+mod message;