This e-supplement supports our report "National Security: An Overview of Professional Development Activities Intended to Improve Interagency Collaboration (GAO-11-108)". This e-supplement provides an inventory of professional development activities intended to improve the abilities of personnel from key agencies involved in national security issues to collaborate across organizational lines. For each activity, this e-supplement lists, if available, (1) the providing agency; (2) a description of the activity, including the subject matter addressed, participant time commitment, and delivery mode; (3) the population being targeted for participation; and (4) the number of fiscal year 2009 participants.