The Lesson Study for Accessible Science (LSAS) project created middle school teams comprised of both science and special education teachers who engaged in collaborative work to improve instruction in inclusive classrooms. The intervention is based on Lesson Study, a professional development approach that originated in Japan, which supports the systematic examination of practice and student understanding. Using an experimental design, teams of teachers were randomly assigned to the LSAS intervention or to a wait-list comparison group. The results of this study suggest that science and special educators in the LSAS intervention were able to generate more accommodations for students with learning disabilities, and they increased their ability to set an instructional context and adapt an instructional plan to meet science learning goals for all students in an inclusive classroom. They did not, however, show significant increases in their knowledge of science content or learning disabilities. © 2012 Wiley Periodicals, Inc. J Res Sci Teach 49: 1012–1034, 2012