This literature review examines current practice in reporting school dropout rates and the impact that school dropout may have on adult education programs and policies. First, I investigate the five dropout estimates commonly reported by the U.S. Department of Education (USDOE), examining how these measures vary in their estimation of school dropout. I then review new methods for estimating dropout which reveal school dropout to be a more substantial problem than previously recognized. Finally, I examine ways K-12 school dropout may affect adult basic education (ABE) and General Educational Development (GED) programs and consider how ABE and GED programs and policies may be reformed to deal with the U.S. school dropout problem. (Contains 4 tables.)