An early warning system is a data-based tool that helps predict which students are on the right path towards eventual graduation or other grade-appropriate goals. Through such systems, stakeholders at the school and district levels can view data from a wide range of perspectives and gain a deeper understanding of student data. This "Statewide Longitudinal Data Systems" (SLDS) Spotlight takes a look at some of the early warning system development and expansion work going on in Massachusetts, Maine, and South Carolina. It discusses some of the benefits of using an early warning system and offers tips on the development of this type of system. The content of this brief was derived from an SLDS monthly topical webinar that took place on January 27, 2012.