OBJECTIVE: To assess how a strategy to maximize access to emergency contraceptive pills would affect rates of pregnancy and sexually transmitted infections. METHODS: Sexually active women, 14-24 years old, were randomly assigned to two methods of access to emergency contraceptive pills: increased access (two packages of pills dispensed in advance with unlimited resupply at no charge) or standard access (pills dispensed when needed at usual charges). Participants were followed for 1 year to assess incidence of pregnancy, gonorrhea, chlamydia, and trichomonas. RESULTS: The numbers of women enrolled in the increased and standard access groups were 746 and 744, respectively. More than 93% of participants completed a full year of follow-up. The incidence of pregnancy was similar in both groups (increased access group: 9.9/100 woman years, 95% confidence interval [CI] 7.7-12.6; standard access group: 10.5/100 woman years, 95% CI 8.2-13.2). Aggregate rates of gonorrhea, chlamydia, and trichomonas were also similar in the two groups (increased access group: 6.9/100 woman years, 95% CI 5.1-9.1; standard access group: 7.6/100 woman years, 95% CI 5.7-9.9). The increased access group used emergency contraceptive pills substantially more often and sooner after coitus than the standard access group. No other differences were noted between groups in self-reported measures of sexual behavior and contraceptive use. CONCLUSION: This intensive strategy to enhance access to emergency contraceptive pills substantially increased use of the method and had no adverse impact on risk of sexually transmitted infections. However, it did not show benefit in decreasing pregnancy rates. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, www.clinicaltrials.gov, NCT00060463. © 2006 The American College of Obstetricians and Gynecologists.