This book focused on five Federal systems1 that play key and inter-related roles in preparing youth with disabilities as they transition into adulthood - vocational rehabilitation, social security, juvenile justice, behavioral health, and workforce investment. The book was limited to these five systems, rather than examining all of the systems that serve this population, due to financial constraints. This document summarizes each system's role, the extent of its use by the population, and central programs and authorizing legislation. In addition, challenges and recommendations for each system are identified, as are common themes and trends across systems. Table 1: Summary of Barriers, Recommendations, and Trends starting on page 10 summarizes these challenges and recommendations by system, as well as the common themes across systems.