School attendance can be an early indicator that something is going wrong with a student. Gathering, analyzing, and acting on attendance information is a first step toward school improvement. Meanwhile, the majority of the states are moving to build and enhance what are called "early warning systems," intended to flag at-risk students during their formative years to give teachers, administrators, and parents a better chance at getting them back on track toward high school graduation. While there are variations in what data states collect and how it is issued, attendance information is a key common denominator.