In the four-year period 1968 to 1972 most medical schools in the United States initiated programs to increase the enrollment of selected minority group students. Their number increased sixfold in Caucasian-dominated medical schools during these years, and the enrollment of such students rose from 1 to 5.3 percent of the total undergraduate population, with the impetus for this policy originating from within the schools. All schools recruited applicants from among the minority races, and two-thirds of the schools altered their admission procedures, often so as to permit minority group participation in the selection process. Schools which modified their procedures in this manner had the highest proportions of these students. Three-fourths of the schools changed their admission criteria, and most of them provided special tutoring and other academic support. Ninety percent of the schools evaluated their programs as at least somewhat successful.