Research shows that students who experience discipline that removes them from the classroom are more likely to repeat a grade, drop out of school, and become involved in the juvenile justice system. This can result in decreased earning potential and added costs to society (lost tax revenue and incarceration). The Government Accountability Office (GAO) was asked to review the use of discipline in schools. This report examines: (1) patterns in disciplinary actions among public K-12 schools; (2) challenges selected school districts have with student behavior and how they approach school discipline; and (3) actions the Departments of Education and Justice have taken to identify and address disparities or discrimination in school discipline. GAO analyzed discipline data from nearly all public schools for school year 2013-14 from the Department of Education's Civil Rights Data Collection and interviewed federal and state officials, as well as officials from 5 districts and 19 schools in California, Georgia, Massachusetts, North Dakota, and Texas. GAO also reviewed federal laws and a non-generalizable sample of seven recently resolved federal school discipline investigations. Overall, black students, boys, and students with disabilities were disproportionately disciplined in public schools. These disparities were widespread and persisted regardless of type of disciplinary action, level of school poverty, or type of public school attended. The school districts reported changing their approach to discipline in order to address behavior challenges.