As a result of the U.S. Department of Education's near one-billion-dollar investment in the "Teaching American History" ("TAH") grant program since 2001, almost 1,200 projects have taken place in school districts around the country with the important aim of improving the teaching of American history in K-12 classrooms. The study reported in this article concerns the sustained impact of one such project. The principle partners in the three-year Model Collaboration: Rethinking American History (McRAH) program were a high-needs school district, a small liberal arts college, and a nationally recognized urban historical society. The study was designed to measure the impact of the project in terms of the "adoption" of the strategies in teachers' classrooms and the "beliefs," "attitudes," "concerns," or "comfort level" of the teachers with these strategies. Conclusions on the sustainability of the use of the strategies are presented.