This work of the Council of Chief State School Officers (CCSSO) assists states in improving evaluations of the quality of professional development for teachers, and especially evaluations for programs and activities aimed toward improving teaching of K-12 mathematics and science. The current policy emphasis on improving the quality of professional development for teachers is driven by the demand for highly qualified teachers in every classroom and the need to upgrade knowledge and skills of teachers for standards-based instruction. States have strongly expressed a need for effective evaluation designs that will measure impact as well as inform program developers about effective practices. CCSSO is studying current professional development programs for teachers across the states in relation to research-based characteristics of high quality, effective activities and methods of evaluation.