An underlying premise of many resource adequacy studies is that reaching a specified set of educational outcomes is directly dependent on the level of resources. This article analyzes resource allocation practices among successful schools, low-performing schools, and average public schools in California. We find that differences in traditional resource measures are not able to explain the sharp differences in student achievement among these schools. While unmeasured differences in student characteristics in these schools may explain part of the difference in achievement, the schools also differ dramatically in their effectiveness even though they have very similar expenditure levels. The conclusion is not that resources do not matter. They do, but only when used wisely. This article also delves into what successful schools are doing that might explain their success.