This study investigated the experiences of a group of pre-service secondary science teachers in learning to teach in culturally diverse contexts. The pre-service teachers were all assigned to placements within a large, urban, culturally diverse public high school and paired with mentor teachers. Through one-on-one interviews, the pre-service teachers were asked to recount and evaluate their experiences, as well as to respond to research-informed deficit beliefs about urban and culturally diverse students and communities. Through critical discourse analysis, the pre-service teachers were characterized as establishing particular positionalities in regards to learning to teach within the culturally diverse context of the high school. The pre-service teachers were, furthermore, characterized as establishing particular positionalities in regards to select deficit beliefs that were discussed in the interviews. The role of agency and institutional power structures in supporting or constraining the positionalities established by the pre-service teachers was also considered. Major implications from this study include the need for teacher education programs to address gaps between pedagogical theory and practice enacted or observed in classrooms; the need to facilitate stronger systems of support for pre-service teacher education from the school-based administration; and positionalities, as indicators of more deeply held beliefs, and how these beliefs may influence teaching and learning.