To elucidate the factors that might influence compliance with oral contraceptive use among sexually active adolescents, we undertook a study of 209 unmarried adolescents initiating use of oral contraceptives in three different settings: an inner-city adolescent clinic (I), a birth control clinic in a midsized industrial city (II), and a suburban private practice (III). At the three-month follow-up visit, factors associated with compliance included older age, suburban residence, white race, health care in the suburban private practice, payment status, prior use of contraception, mother's unawareness of oral contraceptives, married parents, older boyfriend, lack of worry about being pregnant, and satisfaction with pill use. Compliance at long-term follow-up (13.5 ± 3.7 months) was additionally associated with educational goals, father's education level, and absence of side effects. Ten pregnancies occurred during the study period among noncompliant site I patients. Inner-city clinic patients were at high risk of noncompliance and unplanned pregnancy.