This paper reports on a partnership based approach for preparing pre-service primary teachers to teach science. It involved forming three-way or "triadic" partnerships, consisting of a final year pre-service primary teacher and an in-service colleague, to teach science in the colleague teacher's classroom, with the support of a teacher-educator. The pre-service teachers had to collaboratively plan, develop and deliver a sequence of science lessons and take major responsibility for teaching a 90 minute science lesson, at least once a week over a six week period. The data was collected during 2007 and 2008. The pre-service teachers kept a reflective journal of their experiences using a process devised to guide and support them. The results indicated improved attitudes to and confidence in teaching science for the pre-service teachers and their in-service colleagues. The results indicate triadic partnership approach may be an effective way to support teacher professional learning in science. (Contains 6 tables and 1 figure.)