diff --git a/docs/deployment/http.mdx b/docs/deployment/http.mdx
index 2383d987d..d146ac62d 100644
--- a/docs/deployment/http.mdx
+++ b/docs/deployment/http.mdx
@@ -513,11 +513,66 @@ When deploying to production, you'll want to optimize your server for performanc
 # Run with basic configuration
 uvicorn app:app --host 0.0.0.0 --port 8000
 
-# Ensure stateless HTTP mode is enabled (stateless_http=True)
-# Run with multiple workers for production
+# Run with multiple workers for production (requires stateless mode - see below)
 uvicorn app:app --host 0.0.0.0 --port 8000 --workers 4
 ```
 
+### Horizontal Scaling
+
+<VersionBadge version="2.10.2" />
+
+When deploying FastMCP behind a load balancer or running multiple server instances, you need to understand how the HTTP transport handles sessions and configure your server appropriately.
+
+#### Understanding Sessions
+
+By default, FastMCP's Streamable HTTP transport maintains server-side sessions. Sessions enable stateful MCP features like [elicitation](/servers/elicitation) and [sampling](/servers/sampling), where the server needs to maintain context across multiple requests from the same client.
+
+This works perfectly for single-instance deployments. However, sessions are stored in memory on each server instance, which creates challenges when scaling horizontally.
+
+#### Without Stateless Mode
+
+When running multiple server instances behind a load balancer (Traefik, nginx, HAProxy, Kubernetes, etc.), requests from the same client may be routed to different instances:
+
+1. Client connects to Instance A → session created on Instance A
+2. Next request routes to Instance B → session doesn't exist → **request fails**
+
+You might expect sticky sessions (session affinity) to solve this, but they don't work reliably with MCP clients.
+
+<Warning>
+**Why sticky sessions don't work:** Most MCP clients—including Cursor and Claude Code—use `fetch()` internally and don't properly forward `Set-Cookie` headers. Without cookies, load balancers can't identify which instance should handle subsequent requests. This is a limitation in how these clients implement HTTP, not something you can fix with load balancer configuration.
+</Warning>
+
+#### Enabling Stateless Mode
+
+For horizontally scaled deployments, enable stateless HTTP mode. In stateless mode, each request creates a fresh transport context, eliminating the need for session affinity entirely.
+
+**Option 1: Via constructor**
+
+```python
+from fastmcp import FastMCP
+
+mcp = FastMCP("My Server", stateless_http=True)
+
+@mcp.tool
+def process(data: str) -> str:
+    return f"Processed: {data}"
+
+app = mcp.http_app()
+```
+
+**Option 2: Via `run()`**
+
+```python
+if __name__ == "__main__":
+    mcp.run(transport="http", stateless_http=True)
+```
+
+**Option 3: Via environment variable**
+
+```bash
+FASTMCP_STATELESS_HTTP=true uvicorn app:app --host 0.0.0.0 --port 8000 --workers 4
+```
+
 ### Environment Variables
 
 Production deployments should never hardcode sensitive information like API keys or authentication tokens. Instead, use environment variables to configure your server at runtime. This keeps your code secure and makes it easy to deploy the same code to different environments with different configurations.