Mr. Charles Ricks, a Joint Special Operations University (JSOU) Senior Fellow, first compiled this guide over a decade ago and continues to provide updates and revisions so that it remains a valuable reference work for JSOU students, Special Operations Forces (SOF) staff officers, and partners within the interagency (IA) enterprise. This is now the fourth edition of this publication. This new edition recognizes the changing nature of the international security environment and the adaptive and evolutionary nature of the IA process. While counterterrorism and combating terrorism remain essential SOF activities, the IA concepts, principles, and processes discussed here apply similarly to the involvement of SOF across the entire competition continuum and to all SOF core activities. As noted by the fifth SOF Truth, “Most special operations require non-SOF support.” That reality continues to form the basis for this guide as it addresses SOF IA engagement across the entire international competition continuum.