This study reports on the introduction of inquiry-based science education (IBSE) to the classroom through teacher professional development. The study occurs in three phases. Teachers initially participated in a professional learning community (PLC) in Phase 1 of the study. They then participated in a community of practice (CoP) in Phase 2. In Phase 1 teachers (as a PLC) were introduced to the concept of teaching by inquiry and delivered Topic 1 to students in the junior cycle of secondary school. Teachers and students encountered challenges. This did not deter most of the teachers who continued to the next phase. The teachers in Phase 2 became part of a CoP that developed resources for two more inquiry based topics to be taught by them in the classroom. Professional development of science teachers using CoP appeared to be effective as a vehicle for teachers to grow in understanding of IBSE in this study. Teachers continued to implement inquiry learning in other classes outside of the study with different resources and so introduced inquiry at a school department level. CoP may be used as a model for teacher professional development to introduce IBL into the classroom.