Mary Kay Stein holds a joint appointment at the University of Pittsburgh as Professor of Learning Sciences and Policy and Senior Scientist at the Learning Research and Development Center. Her early research focused on classroom-based teaching and learning with the aim of understanding the nature of effective instructional practices in mathematics. In the past decade, Dr. Stein’s research interests have expanded to include the school, district, and policy contexts of teacher learning and professional development. Most notably, she has studied the connections between district policy and classroom practice in New York City’s Community School District #2, as well as districtwide instructional reforms in the San Diego city schools. Currently, she is co-PI of an IERI grant, Scaling Up Mathematics: The Interface of Curricula with Human and Social Capital, that is investigating how the teacher learning demands of different curricula (Everyday Mathematics vs. Investigations) influence teacher learning in large-scale reforms in two urban districts. In 2005, Dr. Stein was named Director of the Learning Policy Center at the University of Pittsburgh.