Security cooperation has long been an important instrument of the U.S. government and the Department of Defense for advancing national security objectives vis-a-vis allies and partner countries, including building critical relationships, securing peacetime and contingency access, and building partner capacity (BPC). One of the key challenges for policymakers and combatant commands is gaining a more complete understanding of the real value of BPC activities. Assessments of prior and ongoing BPC activities, in particular, have become increasingly important given the current fiscal climate and budgetary limitations. But it is no easy task to assess the value of what are essentially qualitative activities, and data limitations severely hinder assessments. The tools available--such as resources, authorities, programs, processes, and organizational relationships--may or may not be the optimal ones for the delivery of BPC activities to partner countries. This report characterizes security cooperation mechanisms used by combatant commands for BPC, produces a detailed database of the mechanism elements, develops and applies a preliminary means of evaluating the effectiveness and efficiency of select mechanisms, and draws on the analysis from the case studies to recommend ways to improve the effectiveness and efficiency of those mechanisms in the future.