This study investigates the relationship, if any, between teacher participation in a targeted professional development program and changes in participants' instructional practice and their pupils' attitudes to learning primary science. The program took place over a 2-year period in 15 small rural schools in the West of Ireland. Data sources include teacher and pupil questionnaires, semi-structured interviews and informal classroom observations. The findings reveal that as a result of their involvement in the program, (a) teachers' instructional practice in science lessons became more inquiry-based and they were engaging their pupils in substantially more hands-on activities in science lessons and (b) pupils developed more positive attitudes towards learning science. The findings from this study add to what is known about delivering effective professional development. Author abstract