Several factors may interfere with the effective collaboration between universities and K-12 schools, a key element in the process of establishing and operating professional development schools (PDSs). These factors relate to differences in school and university cultures and the impact of these differences on the respective faculties. Among the differences are differences in work tempo, professional focus, career reward structure, sense of personal power and efficacy, academic freedom, and approach to preservice teacher education. Investigation of four professional development school sites reveals a variety of strategies that schools and universities (Virginia Commonwealth University, Kansas State University, Michigan State University, and the University of Northern Colorado) are using to overcome barriers to collaboration. This booklet provides a rationale for professional development schools, lists common characteristics, briefly describes examples of successful operations, places PDSs in historical context, identifies factors that contribute to successful collaboration, and suggests things that school administrators can do to achieve successul collaboration. (IAH)