DISCOVER is the computer-assisted career guidance program of the American College Testing Program. A comprehensive review of research on the effectiveness of DISCOVER found that it increases users' vocational identity, level of career development, and career decision-making self-efficacy. Somewhat mixed findings emerged regarding the effectiveness of DISCOVER as a tool for increasing career decidedness, occupational certainty, career maturity, and career exploration. DISCOVER appears to be most effective when used in conjunction with additional career exploration and planning activities (e.g., individual counseling and group workshops). This report includes summaries of the 26 investigations evaluating DISCOVER's effectiveness that have been published between 1978 and 1998. The populations studied included middle school students, high school students, college students, and adults in career transition. Suggestions for future research are discussed, with a particular focus on improving methodological limitations of previous research in this domain. An appendix contains a chronology of DISCOVER versions. (Contains 2 tables and 69 references.) (Author/SLD)