Little empirical research has focused on whether comprehensive service programs for pregnant teenagers and teenage parents have helped to prevent or reduce the occurrence of subsequent pregnancies. This 4-year follow-up study evaluated what impact 8 services provided by a nonprofit agency have had on preventing repeat pregnancies, including increasing the length of time before a subsequent pregnancy. Subjects (N=52) were unmarried black adolescent girls who were pregnant with their first child at the time they became affiliated with the agency. Based on agency records and staff interviews, the adolescent mothers were rated on their average level of involvement in each of the 8 services during the subsequent 2-year period after their initial referral to the agency. The adolescents' repeat-pregnancy outcomes were then assessed 4 years after their initial referral to the agency. The results of regression analyses indicated that adolescent mothers who had a higher level of participation in two combined pre- and post-birth service programs were significantly more likely to experience a longer period of time after their first pregnancy without a repeat or subsequent pregnancy. (Author/ABL)