State and local education agencies across the country face challenges related to understanding and managing their teaching staff to best help students learn. Statewide longitudinal data systems (SLDSs) offer valuable information about teacher labor markets that can be used to analyze supply and demand, inform budget and staffing decisions, and recruit qualified teachers in critical subject areas. Many states have started to combine data from local and state staff information systems as well as postsecondary educator preparation programs to gain greater insight into the qualifications and placement of their teachers. This brief describes three of the most common questions about teacher labor markets that state education agencies seek to answer with SLDS data. It also provides examples of how states are gathering, reporting, and using teacher labor market information. [Contributions to this report were made by Marsha Lewis, Jay Pennington, Shannon Stackhouse, Angie Tombari, Corey Chatis, Carla Howe, and Kathy Gosa.]