Research on college student attrition and retention is reviewed. Overall dropout rates and the reasons students give for dropping out are examined, and an attempt is made to assess the outcomes of going straight through college, as opposed to dropping out, temporarily leaving school, and not going to college at all. The demographic, academic, motivational, and personal characteristics of students who are likely to drop out are examined, along with the effect of the general college environmental factors on persistence. College programs designed to upgrade the level of educational service and encourage students to remain in college are described. The programs concern: pre-enrollment information, admissions, college costs and ways to meet them, orientation, faculty and student interaction, academic programs, counseling and advising, career development, campus activities, housing, the withdrawal procedure, two-year colleges, and administration of the retention program. Students' reasons for dropping out include academic matters, financial difficulties, motivational problems, personal considerations, dissatisfaction with college, military service, and full-time jobs. The evidence indicates that college does make a difference in improvement in self-image, social maturity, interests, competence, and employment. A chart indicates what the last 50 years of retention research have shown about the types of students who are more likely to persist and the types who are less likely to persist. An extensive bibliography is included. (SW)