In 2015-16, the high school graduation rate reached a record high of 84 percent (U.S. Department of Education 2017). Despite the gains, over half a million students still drop out of high school each year (U.S. Department of Education 2015). High schools have adopted various strategies designed to keep students who are at risk of not graduating in school and on track for earning the credits required to graduate. "At-risk" students are defined as those failing to achieve basic proficiency in key subjects or exhibiting behaviors that can lead to failure and/or dropping out of school. Dropout prevention strategies are diverse; they vary in type of program, services offered, frequency, intensity, and duration of contact with target students. The U.S. Department of Education (Department) sponsored the National Survey on High School Strategies Designed to Help At-Risk Students Graduate (HSS), which aimed to provide descriptive information on the prevalence and characteristics of dropout prevention strategies for at-risk students. The survey collected data in the 2014-15 school year from a nationally representative sample of 2,142 public high schools and focused on 13 specific high school improvement strategies identified by a panel of external experts and senior Department officials. All findings are based on self-reported data from school principals. This brief on academic support classes is the twelfth in a series of briefs with key findings about these high school improvement strategies.