diff --git a/README.md b/README.md
index 67e130f82..02c4a8edd 100644
--- a/README.md
+++ b/README.md
@@ -11,6 +11,28 @@ The autogenerated OSAL user's guide can be viewed at <https://github.com/nasa/cF
 
 ## Version History
 
+
+### Development Build: v5.1.0-rc1+dev501
+
+- include doxygen targets locally
+- resolve discrepancies between timer API and unit tests
+- Ensure correlation between the test cases and documented return values for the OSAL timer API.
+- resolve discrepancies between binsem API and unit tests
+- add missing clock retcode tests
+- resolve discrepancies between common API and unit tests
+- resolve discrepancies between countsem API and unit tests
+- resolve discrepancies between dir API and unit tests
+- resolve discrepancies between module API and unit tests
+- resolve discrepancies between mutex API and unit tests
+- resolve discrepancies between queue API and unit tests
+- resolve discrepancies between task API and unit tests
+- resolve discrepancies between timebase API and unit tests
+- check misc API return codes
+- Rename CodeQL cFE Build and add Duplicate Job
+- filter only whole words for keyword match
+- update OSAL Config Guide link
+- See <https://github.com/nasa/osal/pull/1058> and <https://github.com/nasa/cFS/pull/263>
+
 ### Development Build: v5.1.0-rc1+dev458
 
 - Adds Counting Semaphore Test with timeouts
diff --git a/src/os/inc/osapi-version.h b/src/os/inc/osapi-version.h
index d72502631..b9925b89d 100644
--- a/src/os/inc/osapi-version.h
+++ b/src/os/inc/osapi-version.h
@@ -36,7 +36,7 @@
 /*
  * Development Build Macro Definitions
  */
-#define OS_BUILD_NUMBER   458
+#define OS_BUILD_NUMBER   501
 #define OS_BUILD_BASELINE "v5.1.0-rc1"
 
 /*