To address the dropout crisis requires a better understanding of why students drop out. Although dropouts themselves report a variety of reasons for leaving school, these reasons do not reveal the underlying causes, especially multiple factors in elementary or middle school that may influence students' attitudes, behaviors, and performance in high school prior to dropping out. To better understand the underlying causes behind students' decisions for dropping out, this study reviewed the past 25 years of research on dropouts. The review is based on 203 published studies that analyzed a variety of national, state, and local data to identify statistically significant predictors of high school dropout and graduation. Although in any particular study it is difficult to demonstrate a causal relationship between any single factor and the decision to quit school, a large number of studies with similar findings does suggest a strong connection. The research review identified two types of factors that predict whether students drop out or graduate from high school: factors associated with individual characteristics of students, and factors associated with the institutional characteristics of their families, schools, and communities.