A comprehensive description--at the national level--of those who applied for admission to the 1976-77 freshmen class of U.S. medical schools is given in this report. In order to relate this 1976-77 applicant cohort (and those accepted from it) to certain social trends in medical education and to continue monitoring changes in the size of applicant pools and first-year classes, the study also compares the 1976-77 pool (42,155 applicants) with the previous year's end and for certain variables, traces trends over the past five years. Data for the study were compiled by the Association of American Medical Colleges (AAMC) and are maintained in the Medical Student Information Service (MSIS). Data are reported on: (1) application activity (applicants and applications, first-time and repeat applicants, and available spaces); (2) demographic characteristics of applicants (residence, age, women applicants, racial/ethnic groups, size of hometown, marital status, and citizenship); (3) academic background (undergraduate college major, highest degree, and academic ability); (4) socioeconomic background (parental income and occupations); and (5) career plans (general plans, specialization plans, expected character of medical practice, and expected location of medical practice). A glossary and bibliography are appended. (LBH)