This study investigates a project-based learning (PBL) approach to teaching evolution to inform efforts in teacher preparation. Data analysis of a secondary biology educator teaching evolution through a PBL approach illuminated: (1) active student voice, which allowed students to reflect on their positioning on evolution and consider multiple perspectives; (2) premature evaluative thinking actually inhibited the students' cognitive engagement with the theory; (3) discussing evolution as a false dichotomy in science, rather than a social controversy; and (4) collaborative relationships in the PBL enhanced procedural types of cognitive engagement. Implications for preparing future science teachers to structure PBL in order to foster more cognitive engagement with socially controversial topics are discussed. (Contains 1 table and 2 footnotes.)