The impact of higher education on the cognitive and social development of students was studied in three experiments. A longitudinal comparison of moral reasoning development in the four years after high school among those who did and did not attend college was undertaken. Instruments used were the Reflective Judgment Questionnaire, the Concept Mastery Test, the Defining Issues Test, and the Sentence Completion Test of ego development. Over the first two years after high school, scores of both groups increased by about the same amount. In the second two years, the increase for the college attenders was greater than that for the nonattenders. Additionally, a cross-sectional comparison between undergraduates in liberal arts majors and undergraduates in engineering majors was conducted. On both a measure of verbal reasoning and a measure of complex reasoning about issues that have no simple right or wrong answer, seniors in both majors scored higher than freshmen. The senior-freshmen difference suggested a similar amount of growth in both kinds of majors. The third study assessed the impact of graduate education on cognitive and cognitive-social developmental measures. Advanced graduate students, first-year graduate students, and college graduates who had not entered graduate school were compared using five instruments measuring reflective judgment, moral reasoning development, ego development, verbal reasoning, and socioeconomic status. Age and selection appeared to explain differences on the measures between beginning and advanced students and between students and nonstudents. Theories and research relating to moral development, ego development and reflective judgment style are reviewed. Although methodological flaws in the research are acknowledged, among the conclusions are that people in college grow in moral reasoning (and at a faster rate than non-college attenders), and that college seniors do not differ significantly from freshmen in ego development. A bibliography is appended. (Author/SW)