This study explored how six preservice teachers who participated as interns in a Professional Development School (PDS) program experienced learning to teach in the PDS context. The paper explores the scholarship of learning to teaching, highlighting the disjuncture between the complexity and contexts of school-based practicums, restructuring of teacher preparation programs, and current research. It proposes a grounded theory methodology for studying interns' experiences. Data were collected through individual interviews, participant observation in the field, and document analysis. Findings resulted in a model of learning to teach that involves learning about teaching and how to teach and learning about how to be a teacher (context-appropriation theory). The paper illustrates these two central categories, strategies, and stages of intern development with specific examples. It offers a model of learning to teach illuminated by newly emerging understandings portrayed by participating preservice teachers. Assertations include: at the end of the internship, PDS interns attain a stage of preservice teacher development that is beyond mastery; PDS interns learn about teaching and how to teach primarily through mentoring from a designated mentor and university supervisor; and PDS interns understand how a school functions as an organization. (Contains 53 references.) (SM)