diff --git a/docs/guides/messaging.md b/docs/guides/messaging.md
index c91e816e..e38f4425 100644
--- a/docs/guides/messaging.md
+++ b/docs/guides/messaging.md
@@ -148,6 +148,16 @@ dereference:
 The responder is just a fancy listener, and can be deregistered the
 same way as a listener.
 
+## Concurrency
+
+Listeners can have multiple threads invoking their handler as messages
+are consumed. You control how many with the `:concurrency` option
+provided by [[listen]] and [[respond]]. By default, it is set to 1 for
+topics and the number of available processors for queues, but for
+IO-bound handlers, you may see better performance as you increase the
+number. It very much depends on what your handler is doing and how
+many messages it needs to process concurrently.
+
 ## Durable Topic Subscriptions
 
 Typically, messages published to a topic are only delivered to
diff --git a/messaging/src/immutant/messaging.clj b/messaging/src/immutant/messaging.clj
index a7d68e2b..52e00bc5 100644
--- a/messaging/src/immutant/messaging.clj
+++ b/messaging/src/immutant/messaging.clj
@@ -227,7 +227,7 @@
 
    The following options are supported [default]:
 
-     * :concurrency  - the number of threads handling messages [1]
+     * :concurrency  - the number of threads handling messages [1 for topics, #cores for queues]
      * :selector     - A JMS (SQL 92) expression matching message metadata/properties [nil]
      * :decode?      - if true, the decoded message body is passed to `f`. Otherwise, the
                        base message object is passed [true]
diff --git a/messaging/src/immutant/messaging/pipeline.clj b/messaging/src/immutant/messaging/pipeline.clj
index 6741584f..1de5c0b0 100644
--- a/messaging/src/immutant/messaging/pipeline.clj
+++ b/messaging/src/immutant/messaging/pipeline.clj
@@ -258,7 +258,7 @@
 
    * :name                a name to use for the step [the current index of the fn]
    * :concurrency         the number of threads to use, overriding the pipeline
-                          setting [1]
+                          setting [#cores]
    * :decode?             if false, the raw message object will be passed to
                           this step [true]
    * :error-handler       an error handler function that can override the
@@ -301,7 +301,7 @@
 
    * :concurrency        the number of threads to use for *each* step. Can be
                          overridden on a per-step basis - see the 'step'
-                         function. [1]
+                         function. [#cores]
    * :error-handler      a function that will be called when any step raises
                          an exception. It will be passed the exception and
                          the argument to the step. Without an error-handler,
diff --git a/project.clj b/project.clj
index defbe02e..8b167528 100644
--- a/project.clj
+++ b/project.clj
@@ -91,7 +91,7 @@
                         clj-http                   "1.0.1"
 
                         ;; org.projectodd.wunderboss  "0.4.1"
-                        org.projectodd.wunderboss  "1.x.incremental.220"
+                        org.projectodd.wunderboss  "1.x.incremental.224"
                         ;; org.projectodd.wunderboss  "0.5.1-SNAPSHOT"
 
                         org.immutant               :version