With the passage of the No Child Left Behind Act (NCLB), state education agencies (SEAs) and local educational agencies (LEAs) have stepped up activities to broadly expand their data collection and reporting systems. The Data Quality Campaign (DQC) has advocated strongly for states to build robust student-level longitudinal data systems based on standards and common definitions that address 10 essential elements provided in this report. This brief also outlines (1) Nine tips for making data accessible and useful, and (2) Lessons learned from leading states for developing reporting and analysis tools. It is widely acknowledged that vital policy conversations now under way-- conversations about increasing the rigor and relevance of high school, improving teacher quality, promoting higher graduation rates and reducing achievement gaps--cannot be successful unless they are informed by reliable longitudinal data. (Contains 4 footnotes and 5 resources.)