diff --git a/src/Dispatching/DispatchStack.php b/src/Dispatching/DispatchStack.php
index 6bf2cd5..c841d0f 100644
--- a/src/Dispatching/DispatchStack.php
+++ b/src/Dispatching/DispatchStack.php
@@ -44,7 +44,7 @@ class DispatchStack implements DispatchStackInterface
      *
      * When the stack is dispatched empty, or when all middleware in the stack
      * call the $next argument they were passed, this method will call the
-     * $next it receieved.
+     * $next it received.
      *
      * When any middleware in the stack returns a response without calling its
      * $next, the stack will not call the $next it received.
diff --git a/src/Dispatching/DispatchStackInterface.php b/src/Dispatching/DispatchStackInterface.php
index 953281c..6cffda5 100644
--- a/src/Dispatching/DispatchStackInterface.php
+++ b/src/Dispatching/DispatchStackInterface.php
@@ -32,16 +32,16 @@ interface DispatchStackInterface extends MiddlewareInterface
      * returns the response unchanged.
      *
      * When any middleware returns a response without calling the $next
-     * argument it recieved, the stack instance MUST stop propogating and MUST
+     * argument it received, the stack instance MUST stop propagating and MUST
      * return a response without calling the $next argument passed to __invoke.
      *
      * This method MUST call the passed $next argument when:
      * - The stack is empty (i.e., there is no middleware to dispatch)
-     * - Each middleware called the $next that it receieved.
+     * - Each middleware called the $next that it received.
      *
      * This method MUST NOT call the passed $next argument when the stack is
      * not empty and any middleware returns a response without calling the
-     * $next it receieved.
+     * $next it received.
      *
      * @param ServerRequestInterface $request
      * @param ResponseInterface $response
diff --git a/src/Dispatching/DispatcherInterface.php b/src/Dispatching/DispatcherInterface.php
index f1fe1f7..28bd113 100644
--- a/src/Dispatching/DispatcherInterface.php
+++ b/src/Dispatching/DispatcherInterface.php
@@ -29,7 +29,7 @@ interface DispatcherInterface
      *
      * Implementation MAY dispatch other types of middleware.
      *
-     * When an implementation receives a $middware that is not of a type it can
+     * When an implementation receives a $middleware that is not of a type it can
      * dispatch, it MUST throw a DispatchException.
      *
      * @param mixed $middleware
diff --git a/src/MiddlewareInterface.php b/src/MiddlewareInterface.php
index b56407b..4f700be 100644
--- a/src/MiddlewareInterface.php
+++ b/src/MiddlewareInterface.php
@@ -17,17 +17,18 @@ interface MiddlewareInterface
      * $next is a callable that expects a request and response as parameters
      * and returns a response. Calling $next forwards a request and response
      * to the next middleware in the sequence (if any) and continues
-     * propagation; returning a response without calling $next halts propgation
-     * and prevents subsequent middleware from running.
+     * propagation; returning a response without calling $next halts
+     * propagation and prevents subsequent middleware from running.
      *
-     * Implementations MAY call $next to continue propagation. After calling
-     * $next, implementations MUST return the response returned by $next or
-     * use $next's returned response to determine the response it will
-     * ulitimately return. Implementations MUST NOT call $next and disregard
-     * $next's returned response.
+     * Implementations SHOULD call $next to allow subsequent middleware to act
+     * on the request and response. Implementations MAY further alter the
+     * response returned by $next before returning it.
      *
-     * Implementaitons MAY return a response without calling $next to halt
-     * propagation.
+     * Implementations MAY return a response without calling $next to prevent
+     * propagation (e.g., for error conditions).
+     *
+     * Implementations SHOULD NOT call $next and disregard the response by
+     * returning an entirely unrelated response.
      *
      * @param ServerRequestInterface $request
      * @param ResponseInterface $response
diff --git a/src/Transmission/Transmitter.php b/src/Transmission/Transmitter.php
index 6666257..b9b47af 100644
--- a/src/Transmission/Transmitter.php
+++ b/src/Transmission/Transmitter.php
@@ -28,7 +28,7 @@ class Transmitter implements TransmitterInterface
      *
      * This method will also provide a Content-length header if:
      *   - Response does not have a Content-length header
-     *   - Response does not have a Tranfser-encoding: chunked header
+     *   - Response does not have a Transfer-encoding: chunked header
      *   - Response body stream is readable and reports a non-null size
      *
      * @param ServerRequestInterface $request
@@ -69,7 +69,7 @@ class Transmitter implements TransmitterInterface
         // Add a Content-length header to the response when all of these are true:
         //
         // - Response does not have a Content-length header
-        // - Response does not have a Tranfser-encoding: chunked header
+        // - Response does not have a Transfer-encoding: chunked header
         // - Response body stream is readable and reports a non-null size
         //
         if (!$response->hasHeader("Content-length")