diff --git a/launcher/src/main.rs b/launcher/src/main.rs
index 8367ef81..de2b3f64 100644
--- a/launcher/src/main.rs
+++ b/launcher/src/main.rs
@@ -382,6 +382,11 @@ struct Args {
     #[clap(long, env)]
     tokenizer_config_path: Option<String>,
 
+    /// Enable outlines grammar constrained generation
+    /// This is a feature that allows you to generate text that follows a specific grammar.
+    #[clap(long, env)]
+    grammar_support: bool,
+
     /// Display a lot of information about your runtime environment
     #[clap(long, short, action)]
     env: bool,
@@ -1051,6 +1056,11 @@ fn spawn_webserver(
         args.model_id,
     ];
 
+    // Grammar support
+    if args.grammar_support {
+        router_args.push("--grammar-support".to_string());
+    }
+
     // Tokenizer config path
     if let Some(ref tokenizer_config_path) = args.tokenizer_config_path {
         router_args.push("--tokenizer-config-path".to_string());
diff --git a/router/src/main.rs b/router/src/main.rs
index a1f8d97b..6bd86d58 100644
--- a/router/src/main.rs
+++ b/router/src/main.rs
@@ -75,6 +75,8 @@ struct Args {
     ngrok_edge: Option<String>,
     #[clap(long, env, default_value_t = false)]
     messages_api_enabled: bool,
+    #[clap(long, env, default_value_t = false)]
+    grammar_support: bool,
 }
 
 #[tokio::main]
@@ -108,6 +110,7 @@ async fn main() -> Result<(), RouterError> {
         ngrok_authtoken,
         ngrok_edge,
         messages_api_enabled,
+        grammar_support,
     } = args;
 
     // Launch Tokio runtime
@@ -359,6 +362,7 @@ async fn main() -> Result<(), RouterError> {
         ngrok_edge,
         tokenizer_config,
         messages_api_enabled,
+        grammar_support,
     )
     .await?;
     Ok(())
diff --git a/router/src/server.rs b/router/src/server.rs
index 6e042c4e..bcf17f46 100644
--- a/router/src/server.rs
+++ b/router/src/server.rs
@@ -780,6 +780,7 @@ pub async fn run(
     ngrok_edge: Option<String>,
     tokenizer_config: HubTokenizerConfig,
     messages_api_enabled: bool,
+    grammar_support: bool,
 ) -> Result<(), axum::BoxError> {
     // OpenAPI documentation
     #[derive(OpenApi)]
@@ -841,6 +842,7 @@ pub async fn run(
         max_top_n_tokens,
         max_input_length,
         max_total_tokens,
+        grammar_support,
     );
     let generation_health = Arc::new(AtomicBool::new(false));
     let health_ext = Health::new(client.clone(), generation_health.clone());
diff --git a/router/src/validation.rs b/router/src/validation.rs
index a77995df..c97e878a 100644
--- a/router/src/validation.rs
+++ b/router/src/validation.rs
@@ -19,6 +19,7 @@ pub struct Validation {
     max_top_n_tokens: u32,
     max_input_length: usize,
     max_total_tokens: usize,
+    grammar_support: bool,
     /// Channel to communicate with the background tokenization task
     sender: Option<mpsc::UnboundedSender<TokenizerRequest>>,
 }
@@ -32,6 +33,7 @@ impl Validation {
         max_top_n_tokens: u32,
         max_input_length: usize,
         max_total_tokens: usize,
+        grammar_support: bool,
     ) -> Self {
         // If we have a fast tokenizer
         let sender = if let Some(tokenizer) = tokenizer {
@@ -66,6 +68,7 @@ impl Validation {
             max_top_n_tokens,
             max_input_length,
             max_total_tokens,
+            grammar_support,
         }
     }
 
@@ -293,6 +296,11 @@ impl Validation {
             .validate_input(request.inputs, truncate, max_new_tokens)
             .await?;
 
+        // Ensure that grammar is not set if it's not supported
+        if !grammar.is_empty() && !self.grammar_support {
+            return Err(ValidationError::Grammar);
+        }
+
         let parameters = NextTokenChooserParameters {
             temperature,
             repetition_penalty,
@@ -455,6 +463,8 @@ pub enum ValidationError {
     StopSequence(usize, usize),
     #[error("tokenizer error {0}")]
     Tokenizer(String),
+    #[error("grammar is not supported")]
+    Grammar,
 }
 
 #[cfg(test)]