I am using WIX and have successfully used a custom action to execute installed file at the end of installer like this: <CustomAction Id="LaunchAfterInstall" FileKey="foobar.exe" ExeCommand="parameters" Execute="immediate" Impersonate="yes" Return="asyncNoWait" /> <Property Id="WIXUI_INSTALLDIR" Value="INSTALLLOCATION"/> <UIRef Id="WixUI_InstallDir" /> <Property Id="WIXUI_EXITDIALOGOPTIONALCHECKBOXTEXT" Value="Launch Foobar." /> <UI> <Publish Dialog="ExitDialog" Control="Finish" Order="1" Event="DoAction" Value="LaunchAfterInstall">WIXUI_EXITDIALOGOPTIONALCHECKBOX</Publish> </UI> This works well when foobar.exe is in a component in the same wxs file. However what I really want is to execute a file that is installed by a merge module. How do I do this? I can make changes in the merge module, if this helps things.