This paper provides an overview of the research landscape for the kind of professional learning needed for project-based learning to succeed. The evidence is clear that such professional learning must ensure teachers are active, self-directed learners who receive support that is meaningful and relevant to their experiences and context. The authors provide a close examination of the specific professional-learning opportunities available to teachers through the Knowledge in Action (KIA) program. The KIA program, an effective project-based learning (PBL) approach to Advanced Placement (AP) courses, provides sustained support to teachers over the course of a year. That support includes intensive coaching, the chance to reflect on one's practices, and opportunities for teachers to try inquiry-based experiences that are similar to those students experience in a PBL classroom. That particular approach helps teachers make sense of instructional practices that tend to be fairly different from those that are more commonly used in schools.