Three principal factors supported our decision to participate in the piloting of the Pennsylvania Value-Added Assessment System (PVAAS). First, participants needed to have or secure electronic student assessment data. As a very data-oriented school district, we had over five years of longitudinal student data stored electronically for use in our own analyses. However, we believed that more thorough analyses were required to exploit these data fully. Through PVAAS the state promised such analyses at no cost to the district. We believed that this was too important an opportunity to pass up. Second, despite our "below state average" test results, we knew our children were making tremendous gains and our teachers worked very hard. We hoped that an analysis that focused on the value added by the schooling system rather than its overall level would be able to confirm our observations. Third, we believe that properly looked at, appropriate data would allow teachers and principals to improve instruction by providing evidence of the efficacy of alternative approaches. We routinely use student performance data to guide and inform instruction. The PVAAS system promised to provide an easy to use, interactive interface to assist in the task. But to convince teachers to use data effectively in the planning of instruction for their students, they must use, understand, and embrace the data in a safe environment. When the wrong data are used to judge their performance, that trust is violated. Value-added measures assist in the trust factor as teachers can judge their own effect on the students, ruling out other factors.