An abstinence-only intervention aimed at young, urban African-American adolescents successfully delayed sexual initiation among participants in the program, according to a well-designed new study, “Efficacy of a Theory-Based Abstinence-Only Intervention Over 24 Months,” by John B. Jemmott and colleagues. While the evaluated program is the first abstinence-only intervention to demonstrate this positive impact in a randomized control trial, it was not a rigid “abstinence-only-until-marriage” program of the type that, until this year, received significant federal funding. The evaluation, therefore, adds important new information to the question of “what works” in sex education, but it essentially leaves intact the significant body of evidence showing that abstinence-only until-marriage programming that met previous federal guidelines is ineffective.