Postdoctoral training in health service psychology has changed substantially in the past decade. The articles in this special section speak to important questions regarding the purpose and function of advanced training in this field. The intersection of a number of trends, including increased specialization, growth of training programs, and expansion of available postdoctoral positions, introduces several dilemmas to the postdoctoral training community. How do we manage recruitment of postdoctoral residents and selection into training programs and positions? How do we ensure that postdoctoral training provides a pathway to advanced competence in a given specialty or focus area? What are the key components of postdoctoral training that will build effectively on our unique role as scientifically trained mental health practitioners? How can we best counsel interns regarding the array of options in postdoctoral training, or the choice between postdoctoral training and a professional position as a next step in their careers? The articles that follow reflect upon these key questions and help us set a course for the definition of operating principles and effective models for postdoctoral training in health service psychology in the 21st century.