diff --git a/src/OpenTelemetry/CHANGELOG.md b/src/OpenTelemetry/CHANGELOG.md
index 6260596c78c..d7180a12752 100644
--- a/src/OpenTelemetry/CHANGELOG.md
+++ b/src/OpenTelemetry/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## Unreleased
 
+* Modified OpenTelemetrySdkEventSource with the following changes to support activity tracking:
+  * ActivityStarted and ActivityStopped events have been renamed to ActivityStart and ActivityStop respectively. This is to comply with the naming convention for activity tracking.
+  * ActivityStart and ActivityStop use the Start and Stop operation codes (EventOpCode) respectively.
+
 * Fixed an issue where `LogRecord.Attributes` (or `LogRecord.StateValues` alias)
   could become out of sync with `LogRecord.State` if either is set directly via
   the public setters. This was done to further mitigate issues introduced in