For decades since the formation of the defense establishment under the 1947 National Security Act, all U.S. cabinet departments, national security agencies, and military services involved in providing for the common defense have struggled to overcome differences in policy and strategy formulation, organizational cultures, and even basic terminology. Post-September 11, 2001, international systems, security environments, U.S. military campaigns in Afghanistan and Iraq, and the greater Global War on Terrorism have confronted civilian policymakers and senior military officers with a complex, fluid battlefield which demands kinetic and counterinsurgency capabilities. This monograph addresses the security, stability, transition, and reconstruction missions that place the most pressure on interagency communication and coordination. The results from Kabul to Baghdad reveal that the interagency process is in need of reform and that a more robust effort to integrate and align civilian and military elements is a prerequisite for success.