This document chronicles the experience of the National Training Institute (NTI) for Community Youth Work and four of its Building Exemplary Systems for Training Youth Workers (BEST) affiliates in establishing youth development practitioner apprenticeship (YDPA) programs. Part 1 describes the work of NTI and BEST intermediary organizations to lay the groundwork for YDPA programs and the program's preplanning phase. Part 2 discusses the research strategies and activities implemented during the program's 18-month preplanning period. Part 3 describes the national program development and management activities implemented by NTI, presents findings from a review of data reported by BEST site leaders, and describes factors that likely contributed to sites' local progress. Part 4 presents examples of innovations developed by local BEST sites. Part 5 lists key results from the planning period, presents site leaders' reflections regarding opportunities and challenges presented by the initiative, and summarizes next steps for implementation and replication of BEST YDPA programs. Part 6 offers recommendations to YDPA stakeholders. Thirteen charts/figures are included. The following items are appended: BEST YDPA study site profiles, research instruments, on-the-job training product contents, and technical assistance tools; descriptions of U.S. Department of Labor and National YDPA clearinghouse resources; and overviews of the national BEST network and selected national BEST training programs. (MN)