A team of researchers wanted to learn whether AP teachers using a project-based learning (PBL) approach could develop students' deep learning of knowledge and skills while preparing them for their AP exams. They used a randomized controlled trial to evaluate the Knowledge in Action (KIA) project-based curricula for AP courses. KIA students outperformed non-KIA students on AP exams, including within subgroups. Though the shift to PBL required considerable pedagogical changes, teachers and students perceived benefits beyond AP performance, and the majority of teachers planned to continue using PBL after the study. The pattern of results was consistent for two years and in two courses, AP U.S. Government and AP Environmental Science. Results support teacher-driven adoption of KIA for students from both lower- and higher-income households and in both courses.