Roughly 10 percent of U.S. students are chronically absent from the classroom - defined as missing 10 percent or more of the school year. Chronic absenteeism increases achievement gaps at the elementary, middle, and high school levels, particularly for low-income students. This report, from the Everyone Graduates Center, identifies the causes of students' long term absence from the classroom (illness, housing instability, involvement in the juvenile justice system and the lack of consequences for skipping) and details the dire academic consequences for chronically absent students. The report also criticizes the fact that few school districts and states bother to measure and analyzes attendance data and, consequently, overlook and do not act upon chronic absenteeism.