This study had two purposes. The first was to explore teacher knowledge of educational technology through the lens of three components of Shulman's model of teachers' knowledge--content, pedagogical, and pedagogical content knowledge. A second purpose was to investigate the ways in which teacher knowledge was acquired, shared, and used by student teachers and their mentors. By using Shulman's model, a comprehensive depiction of teacher knowledge was constructed and considered. Data for the study were drawn from a 3-month intensive observation period. Results indicate that employment of Shulman's model revealed a set of knowledge derived from and applicable to practice with educational technology. Impact on the field includes a broadening sense of the nature of knowledge of educational technology as well as increased attention to the importance of the student teaching placement and student and mentor teachers' roles within that environment.