This working paper summarizes the results of a study of leadership in elementary and secondary schools. The study focused in particular on instructional leadership – the extent to which school leaders focus on the core activities of teaching and learning – and teacher leadership – the extent to which teachers have input into school decision-making. This paper is drawn from the full report of the study, entitled School Leadership Counts (Ingersoll, Dougherty and Sirinides 2017), available at www.newteachercenter.org.