Initiating motivations to teach are the reasons people choose to become teachers. This study characterized the initiating motivations espoused by a cohort of teacher candidates in a professional development school. The data source consisted of essays in which the teacher candidates explained their reasons for becoming teachers. The analytic method was thematic analysis, which was employed to develop a typology of initiating motivations. Findings indicated a pattern of altruistic and intrinsic types of motivations. Common motivations included the desire to make a difference and positive perceptions of the work of teaching. Few teacher candidates espoused extrinsic motivations. The study expands existing understandings about the characteristics of teacher candidates as learners. It carries implications for professional development schools' efforts to recruit teacher candidates. It also has implications for the clinical education of teacher candidates. The study indicates a need for expanded attention to the significance of the initiating motivations of teacher candidates in professional development schools.