This report summarizes main results from a national study of how leaders in urban school district central offices fundamentally transformed their work and relationships with schools to support districtwide teaching and learning improvement. All three study districts had been posting gains in student achievement and credited their progress, in part, to efforts to radically change their work at the central office level. The authors aimed to understand more specifically what these central offices were doing. The study breaks new ground in educational research by uncovering the daily work practices and activities of central office administrators as they sought not just to make the central office more efficient but also to transform the central office into a support system to help all schools improve the quality of teaching and learning. The findings reveal that leaders in these systems, first and foremost, understood what decades of experience and research have shown: that districts generally do not see districtwide improvements in teaching and learning without substantial engagement by their central offices in helping all schools build their capacity for improvement. Central offices and the people who work in them are not simply part of the background noise in school improvement. Rather, school district central office administrators exercise essential leadership, in partnership with school leaders, to build capacity throughout public educational systems for teaching and learning improvements. The districts in this study were attempting to heed those lessons by engaging in an approach to central office change the authors call "central office transformation." Central office transformation is a far cry from central-office-administration-as-usual. This approach to reform: (1) Focuses centrally and meaningfully on teaching and learning improvement; (2) Engages the entire central office in reform; (3) Calls on central office administrators to fundamentally remake their work practices and their relationships with schools to support teaching and learning improvements for all schools; and (4) Constitutes an important focus for reform in its own right. (Contains 3 tables, 6 figures and 23 footnotes.) [This paper was written with the assistance of Elizabeth Matson, Liza Pappas, and Bethany Rogers.