This chapter, published as part of an extensive report on an experimental college program for low-achieving students, provides a comprehensive review of recent research literature related to low-achievers. Organized into several sections, the review deals with literature on identifying over-and under-achievers, factors related to achievement and under-achievement, predicting achievement, and experimental efforts to improve achievement. Also discussed is literature concerned with academic achievement, college admissions policy, and attrition in higher education. A lengthy bibliography is presented. (For other chapters of this report, see UD 005309, UD 005310, UD 006860, and UD 006861.) (LB)