The purpose of this study was to investigate the relationship between teachers’ participation in constructivist chemistry professional development (PD) and enhancement of content (CK) and pedagogical content knowledge (PCK) (representational thinking and conceptual change strategies) and self-efficacy (PSTE). 69 teachers participated in this study. Results suggest that: (1) constructivist PD meets the needs of teachers of varying CK, and (2) instruction should connect representational models with alternative conceptions, integrating radical and social constructivism.