Research advances in teaching, learning, curriculum, and assessment have not changed the continued underperformance of marginalized students in mathematics education. Culturally responsive teaching is a means of addressing the needs of these students. It is sometimes challenging, however, to convince secondary mathematics teachers about the importance of culture in mathematics education. To contribute to what is known about supporting secondary mathematics teachers in developing a culturally responsive teaching practice, we studied the impacts of a graduate course called Culture in the Mathematics Classroom on 13 teachers enrolled in the course. The course was designed to guide secondary mathematics teachers in understanding and growing their capacity to enact culturally responsive teaching in their classrooms. The purpose of our research was to explore how teachers' perceptions changed as a result of their engagement in the class with respect to understanding the role of culture in knowing and being responsive to their students. Specifically, we examined how each of the four course projects seemed to individually and collectively influence teachers' thinking. Overall, teachers appeared to expand their cultural awareness and dispositions for cultural responsiveness that would support them in knowing and supporting their students in the manner of a culturally responsive teacher. Teachers did not, however, develop some more "advanced" understandings related to power and privilege in society. This study provides researchers and mathematics teacher educators with a potential analytic framework for understanding teacher change with respect to culturally responsive teaching.