Teacher professional learning is of increasing interest as one way to support the increasingly complex skills students need to learn in preparation for further education and work in the 21st century. Sophisticated forms of teaching are needed to develop student competencies such as deep mastery of challenging content, critical thinking, complex problem-solving, effective communication and collaboration, and self-direction. In turn, effective professional development (PD) is needed to help teachers learn and refine the pedagogies required to teach these skills. However, research has shown that many PD initiatives appear ineffective in supporting changes in teacher practices and student learning. Accordingly, the authors set out to discover the features of effective PD. This paper reviews 35 methodologically rigorous studies that have demonstrated a positive link between teacher professional development, teaching practices, and student outcomes. The authors identify the features of these approaches and offer rich descriptions of these models to inform those seeking to understand the nature of the initiatives. In this review, they find seven widely shared features of effective professional development. Such professional development: (1) Is content focused; (2) Incorporates active learning; (3) Supports collaboration; (4) Uses models of effective practice; (5) Provides coaching and expert support; (6) Offers feedback and reflection; and (7) Is of sustained duration. [This report was written with assistance from Danny Espinoza. For the research brief, see ED606741.]