Book excerpt: This project introduces the reader to the command of the United States. If you have time to study only one command, this is the one and this ToolBook is the vehicle to get you there. The Combatant Commands Informational Series is designed to identify the roles, functions, responsibilities and Area of Responsibility (AOR) of the unified commands. Its primary focus is to introduce potential joint staff officers to these commands. Additionally, this research should also prove valuable to the military education system as curriculum support material, specifically, Air Command and Staff College's Joint Operations and Strategic Structures Regional Studies curriculums, as well as, the ACSC Distance Learning programs. Our research centered upon USACOM's missions and roles. Students conducted extensive research including interviews with command staff experts, library searches and.