In 1995, 17 graduate students at the University of Wisconsin attended a summer course titled Education 570: Integrating the Curriculum. This course was based on a constructivist view of knowledge development, and participating teachers represented a wide range of subject areas and grade levels. A study of participating teachers followed 16 teachers through the summer course and subsequent school year. This paper provides case studies of five of these teachers whose participation in the course was monitored through observations, surveys, interviews, and videotapings. Each case study begins with demographic and background information about the teachers, their experiences, and their preliminary beliefs about integration. Descriptions of their integration projects are provided, as are discussions of factors impeding or facilitating implementation of these projects. Questions discussed include: how do teachers define classroom integration?; do teachers change in their thinking about planning for instruction as a result of learning about constructivism and models of integration?; which model of integration did each teacher most embrace, and how was this model implemented in their classrooms?; and how do participants describe the impact of constructivist, integrated instruction on the teachers and students in their schools? (PB)