The composition of Air Force active and reserve forces is often contentious, especially during a force drawdown. This report builds on previous RAND research that found that the distribution of force structure to the active component (AC) and reserve components (RC) in some missions is not cost-optimal. This document seeks to inform force composition decisions by clarifying issues that affect the suitability of missions for assignment to the RC. The authors considered information contrasting AC and RC characteristics on a variety of factors that bear on suitability of mission assignments. From these considerations, the authors distilled criteria that could be used to weigh the suitability of missions for assignment to the RC, and finally they applied these criteria to a representative set of missions.