During the past decade, much has been written about adolescents' use of contraception and their experience of pregnancy. Few researchers, however, have distinguished between the experiences of older and younger adolescents. The purpose of this paper is to provide such a comparison. The data were collected during more than 7,000 visits made by 4,318 patients during almost 5 years of operation of an adolescent contraceptive service in the Washington Heights area of New York City. Characteristics of four groups--14 years and younger, 15-17 years, 18-19 years, and 20-21 years--were examined. The youngest teens initiated sexual intercourse 4 years earlier than the oldest group. Among those 14 or younger, 87 percent had never used contraception, and 9 percent had been pregnant. In the oldest group, more than two-thirds had used a contraceptive method, and three-fifths had already experienced a pregnancy. Results of multivariate analyses indicate that older teens are more likely to come to the clinic for contraception and to be consistent users of the first method of contraception that they select. On the other hand, younger teens are significantly more likely to revisit the clinic and to be pregnant at a second or later visit.