This study examined the knowledge, beliefs and efforts of five prospective teachers to enact teaching science as inquiry, over the course of a one-year high school fieldwork experience. Data sources included interviews, field notes, and artifacts, as these prospective teachers engaged in learning how to teach science. Research questions included 1) What were these prospective teachers' beliefs of teaching science? 2) To what extent did these prospective teachers articulate understandings of teaching science as inquiry? 3) In what ways, if any, did these prospective teachers endeavor to teach science as inquiry in their classrooms? 4) In what ways did the mentor teachers' views of teaching science appear to support or constrain these prospective teachers' intentions and abilities to teach science as inquiry? Despite support from a professional development school setting, the Interns' teaching strategies represented an entire spectrum of practice—from traditional, lecture-driven lessons, to innovative, open, full-inquiry projects. Evidence suggests one of the critical factors influencing a prospective teacher's intentions and abilities to teach science as inquiry, is the teacher's complex set of personal beliefs about teaching and of science. This paper explores the methodological issues in examining teachers' beliefs and knowledge in actual classroom practice. © 2007 Wiley Periodicals, Inc. J Res Sci Teach 44: 613–642, 2007.