Teacher professional development (PD) is central to the realization of the current reform efforts in science education. In this qualitative study, we investigated how educative curriculum materials supported middle school science teachers' learning within the context of a comprehensive PD program focused on the enactment of a reform-based science curriculum. Over a 5-year period, we conducted interviews and collected artifacts from formal courses and complementary project activities. Our analysis revealed that the educative curriculum materials facilitated continued science learning, shaped and scaffolded teachers' pedagogical practices, and extended the PD while the teachers were immersed in the act of teaching. Furthermore, the interrelated project activities along with the involvement of school and district administrators offered the teachers ongoing support and provided multiple opportunities to develop, reinforce, and extend their understanding of the science content, teaching practices, and principles of the curriculum. Our findings have practical implications for the role of educative curriculum materials within the context of comprehensive PD for science teachers.