For most of the Cold War, Special Operations Forces (SOF) occupied an odd niche in the US military. Marginalized by their respective services, they survived by offering civilian policymakers capabilities that the core services did not and often disparaged. Dependent on the imperfect and intermittent protection of civilians, and lacking a unified organizational structure or budget authority, SOF survived by maintaining a very broad portfolio of undesirable missions. No community underwent greater transformation during the second interwar period than did Special Operations. Several major changes propelled Special Operations Command (SOCOM) from a marginal role to the status of a “fifth service.” The rising power and autonomy of SOCOM led it to reprioritize its mission areas. While increased funding has expanded opportunities for nearly all groups in the Special Operations community, SOCOM has invested more heavily in direct action (DA) than in unconventional warfare (UW). The global war on terrorism (GWOT) heightened SOCOM’s autonomy and capability, but these changes, paradoxically, led it to discard many of the missions that policymakers need most in combating terrorism. A strong internal preference for direct action, amplified by early civilian enthusiasm for direct action strategies, skewed the American approach to counterterrorism, leaving national decision-makers long on direct action assets and short on unconventional warfare options. This chapter proceeds in five parts. The first section briefly describes the various US SOF units and their organizational histories. The second presents the rise of joint SOF organizations from 1979 to the end of the Cold War. The third section discusses the experience of SOF during the second interwar period. The fourth section describes the challenges and successes of SOF after September 11. The final section analyzes the problems and prospects for this fifth service and their implications for transformation.