This study reports on the context and impact of the Communication in Science Inquiry Project (CISIP) professional development to promote teachers' and students' scientific literacy through the creation of science classroom discourse communities. The theoretical underpinnings of the professional development model are presented and key professional development activities are described. Data are provided on teachers' fidelity of implementation of the CISIP instructional strategies, their understanding of the nature of science communication, and their ability to write scientific investigation reports. Student data includes an analysis of scientific arguments and the perception of their classroom as a science classroom discourse community. Two instruments to measure fidelity of implementation are introduced; the Discourse in Inquiry Science Classrooms for classroom observations of teachers and My Science Classroom Survey to measure students' perceptions of their teachers' use of the CISIP instructional strategies in their classroom. (Contains 1 table.)