Good, usable data is a must for wise decisionmaking, especially as district and school leaders struggle to meet tough standards aimed at making all students successful as learners. Too often, however, states supply their school leaders indecipherable mountains of test data with no guidance on how to use it. New Mexico, a participant in The Wallace Foundation’s education leadership initiative, is among states leading the way to making data much more useful by increasing the “data literacy” of district and school leaders and by transforming the vast amount of student achievement data it collects into a tool that can help leaders transform instruction and chart the progress of individual students. This lively journalistic account shows how it’s being done.