This paper focuses on some of the "how to's" of professional development for the field of out-of-school programs. The paper examines some of the training experiments in the out-of-school time field and considers questions and issues that must be addressed to create an accessible, viable, and useful system of professional development for this field. Following an introduction, Section II of the paper introduces the elements of a professional development system (core knowledge base, career lattice or matrix, linked system of training programs, training approval system, and registry of practitioners and the training they have completed) and offers recommendations. Section III explores principles that provide important guidance for the establishment of such a system and offers recommendations, while Section IV discusses the creation of a core knowledge base and development of core competencies for the out-of-school time field. This section explores the examples of four such programs: Department of the Army/CDA, Chicago MOST and Chicago Youth Agency Partnership (CYAP) Competencies, Concordia Certificate and Degree Programs, and Karen VanderVen's Developmental Caring. Section V outlines the process of creating a continuum, or linked system, of training. The paper's conclusion notes that in the years ahead, as more programs are developed and as dynamic work on professional development in the out-of-school time field proceeds, much more work will remain to be done. (EV)