Effective professional learning communities are based on the assumption that collective learning and problem solving are key to improving educator practice and student learning. Effective professional learning communities promote the spread of better practices from teacher to teacher as well as school to school, ensuring that more students experience instruction that leads to improved learning. Effective professional learning communities are more likely than individualized learning options to ensure every student experiences great teaching every day. However, not all professional learning communities achieve this outcome. There is considerable variation in how professional learning communities operate, and, as a result, in the outcomes they are able to achieve. Research in school improvement, reports of exemplary practice in the field, and expert observations provide insight into the characteristics