This mixed-methods study examines middle school students' academic language development in the context of a year-long professional development project titled, Developing Content Area Academic Language (DCAAL). The purpose of DCAAL was to partner middle school teachers (n = 8) with a team of university researchers to explore how to integrate academic language support into content area lessons. Research questions and data sources examine both teachers' practice and student gains. Students (n = 303) made significant gains in their academic language knowledge. Furthermore, students who had more than one teacher participating in the project made greater gains, suggesting that students' gains could be attributed at least in part to the professional development. We share research findings as well as specific strategies and approaches that were developed in the context of DCAAL.