This paper explores the perceptions of student teachers regarding the extent to which they consider a constructivist approach supports their learning in science. The research was carried out in two phases and drew on questionnaire and interview data. In Phase 1 a questionnaire was used to collect the views of 34 students regarding the effectiveness of a constructivist approach in facilitating their learning in science. Phase 2 was a more in-depth analysis of factors identified in Phase 1 as influencing the effectiveness of the learning process. The majority of students considered that a constructivist approach was effective in enabling them to learn in science. Findings highlighted the significance of social mediation within constructivist-informed practice, in particular collaborative group work and tutor questioning. These findings are discussed in the context of related research. (Contains 3 tables.)