A growing number of school districts--including large ones like those in Chicago, Dallas, Los Angeles, and Hawaii--have become recent converts to new principal-evaluation systems that tie school leaders' appraisals to student test scores. As of this school year, student achievement accounts for 40 percent to 50 percent of principals' evaluations in each of those school systems, while district leaders in a number of other places are preparing to make similar changes in coming school years. The switch to the new-breed evaluation systems comes on the heels of efforts nationwide to incorporate student-achievement measures into teachers' evaluations. For principals, the move is being prompted by U.S. Department of Education grant programs such as Race to the Top and by No Child Left Behind waivers.