Teach For America's (TFA) shift over the past decade toward measuring and promoting its teachers' ability to boost student performance has caused the organization to reconfigure not just program directors' roles, but nearly all its other support components. It has overhauled its five-week summer training, known as "Institute," to incorporate the new focus. Program directors, who cover small regions, now have fewer corps members--typically around 30--to observe and have more time to respond to their needs. Most recently, TFA has added an on-demand system of Web supports. Such changes have been informed by data that help the organization determine which aspects of its professional development appear to enhance teacher effectiveness and which don't. TFA now unabashedly defines effectiveness in terms of how its teachers' students perform. All corps members are expected to reach at least one of these goals: (1) move student learning forward by 1 1/2 grade levels; (2) close achievement gaps by 20 percent; or (3) ensure that 80 percent of students have met grade-level standards.