This article investigates the extent to which state-mandated high school exit examinations are associated with state-level public high school completion rates in the United States. The authors estimate a series of state and year fixed effects models using a new measure of state-level public high school completion rates and archival information about states' policies on high school exit examinations from 1975 through 2002. The study finds that state high school exit examinations--particularly the "more difficult" examinations that have been implemented recently in some states--are associated with lower public high school completion rates and higher rates of General Educational Development test taking. Furthermore, the study finds that the association between state policies on high school exit examinations and public high school completion grows stronger as states become more racially and ethnically diverse and as poverty rates increase.