This study explored the beliefs about student engagement in mathematics of three Year 5 and 6 teachers, focusing on the shifts that occurred during a 10-week intervention. Data obtained from teacher surveys, interviews, video-recorded workshop observations and artefacts from teachers' classrooms reveal variations in their reactions to the professional learning experiences. Teacher responses were mediated by personal and contextual elements including teacher efficacy beliefs, teacher confidence in mathematics and their conceptions of student engagement. Theories of teacher conceptual change are used to account for variations to teacher beliefs.