Thousands of high schools currently use StudentTracker reports from the National Student Clearinghouse Research Center to measure how many of their graduates go on to college, where, and how many persist to graduation. The reports were designed to help schools to measure their success in preparing students for college, and to evaluate the effectiveness of college access programs and curricula. Increasingly, the results are also being used to inform accountability metrics for schools, districts and states concerned about the performance of secondary schools. In many cases, these metrics are published without fully explaining the source and nature of the data and its limitations. As the most comprehensive source of national student-level college enrollment data, the Clearinghouse is committed to providing transparency regarding the quality, reliability and accuracy of its data, and of the reports that can be derived from it. The belief is that the more the data users understand about the data, the better equipped they will be to use it wisely. This document is intended to inform high schools and districts about what to expect from National Student Clearinghouse data accessed through StudentTracker reports.