This article presents an interview with Michael Barber, a partner at McKinsey & Company, leading its global education practice. He has been working on major challenges of performance, organization, and reform in government and the public services, especially education, in the U.S., U.K., and other countries. Barber was instrumental in preparing the 2007 report "How the World's Best-Performing School Systems Come Out on Top" (McKinsey & Company), an international comparative analysis of the factors that create successful education systems. In this interview, Barber describes four key messages from looking at the best systems in the world.