diff --git a/crates/bevy_ecs/src/system/system_param.rs b/crates/bevy_ecs/src/system/system_param.rs
index fda3684e6e..d4561740d6 100644
--- a/crates/bevy_ecs/src/system/system_param.rs
+++ b/crates/bevy_ecs/src/system/system_param.rs
@@ -49,6 +49,18 @@ pub trait SystemParam: Sized {
 /// Additionally, it is the implementor's responsibility to ensure there is no
 /// conflicting access across all SystemParams.
 pub unsafe trait SystemParamState: Send + Sync + 'static {
+    /// Values of this type can be used to adjust the behavior of the
+    /// system parameter. For instance, this can be used to pass
+    /// values from a `Plugin` to a `System`, or to control the
+    /// behavior of the `System`.
+    ///
+    /// The default configuration of the parameter is set by
+    /// [`SystemParamState::default_config`]. To change it, invoke
+    /// [`FunctionSystem::config`](super::FunctionSystem::config) when
+    /// creating the system.
+    ///
+    /// See [`FunctionSystem::config`](super::FunctionSystem::config)
+    /// for more information and examples.
     type Config: Send + Sync;
     fn init(world: &mut World, system_state: &mut SystemState, config: Self::Config) -> Self;
     #[inline]