This article features Doing What Works (DWW), the largest, most comprehensive, and most insightful repository of effective, research-based instructional practices and other resources currently available to educators. It is a principal's free ticket to accessing an abundance of research-based best practices and school improvement. DWW covers a wide range of topics, everything from data-driven improvement to early childhood education to organizing teaching and reducing behavior problems in elementary school classrooms, and it does so in great depth. DWW encourages principals to improvise and modify the tools and techniques to fit their needs. DWW supplies the empirical evidence. Principals and educators supply the professional wisdom and make the decisions. [This article was written and compiled by the "Principal" magazine editorial team and freelance education writer and editor David Martin.]