The shift from traditional, teacher-led instruction to student-centered, project-based learning is complex. This paper seeks to support the adoption and scaling of rigorous project-based learning (PBL) across grades and subjects by describing some of the essential elements found in high-quality PBL learning environments. These include purposeful and authentic experiences that are strategically sequenced and allow students to revisit concepts and skills over time. Projects should be relevant to learners, their communities, and the broader world. PBL also should be closely tied to academic content and disciplinary practices. High-quality PBL relies on the development of meaningful and supportive relationships. And, as described in this paper, PBL practices must be built around evidence-based approaches.