A mismatch in the late 1990s between the qualifications needed for key general officer positions and the backgrounds of available candidates stimulated RAND research and then an extensive U.S. Air Force effort to improve the development of future senior leaders. In the past, most officers were managed within their career fields and were too narrowly specialized. This monograph summarizes the force development initiative's history and related research efforts that (a) identified colonel positions' needs for multiple (paired) occupational skills and set targets for the numbers of officers who should acquire those skills before they are promoted to colonel and (b) illustrated a four-step approach that can create notably more specific developmental targets for officers at grades from lieutenant through colonel within an occupation or career field. The four steps are as follows: (1) identify and prioritize the types of experience, education, and training that should precede each category of job (identify the demand, at least for the jobs in the field grades -- major, lieutenant colonel, and colonel), now and in the future; (2) ascertain the backgrounds that officers have accumulated (assess the supply); (3) compare supply with demand (gap analysis); and (4) plan ways to close the gaps. These ideas suggest steps that could improve the efficiency and effectiveness of force development for Air Force officers, the enlisted and civilian forces, and the reserve components.