This study examined intern attrition within one urban secondary Professional Development School (PDS). The secondary school was 80 percent minority. Data were collected over 2 years using participant observation, semi-structured interviews, PDS questionnaires, intern personal journals, and document analysis of resignation letters. Informants included five secondary interns who had resigned. All were white and four were female. Interviews were also conducted with eight interns who completed the program, four university faculty, and six school faculty who had worked with these students. Results highlighted several important themes: preparation (course orientation toward theory rather than practice, insufficient training to meet the needs of diverse learners, and an impractical fourth year practicum); support (the need for a climate of support and the lack of consistent mentoring); and internship experience (workplace conditions and a sense of isolation). These results produce a complex web of intern experiences within the PDS, with the primary influences being the cultures of the school and university which are in tension in the intern world. Four realms of experience were critical to interns' decisions to leave or continue: university coursework and preparation, PDS teams, high school classes, and personal context. (Contains 49 references.) (SM)