A case study approach was used to explore the relationship between subject matter knowledge and the acquisition of pedagogical content knowledge in the preparation of preservice elementary mathematics teachers. A preservice elementary teacher was interviewed prior to her mathematics methods course to ascertain her subject matter background and prior pedagogical content knowledge. Both a mathematics educational biography and a structured task interview based on concepts of fractions were employed. Changes in the teacher's subject matter knowledge and pedagogical content knowledge were documented through observations in the mathematics methods course and her field mathematics teaching, and a final structured interview. The study showed that the teacher wanted to do a good job in teaching mathematics but faced many problems that were largely due to her mathematics preparation. Four appendices provide: the Preservice Elementary Mathematics Teaching Information Sheet, the Mathematics Education Biography Interview, the interview task #1 protocol, and the final task interview protocol. (Contains 15 references). (Author/SM)