Abstinence-only sex education teaches that people should be sexually abstinent prior to marriage and that abstinence is the only safe and effective way to avoid unintended pregnancy and sexually transmitted diseases (STDs). Research on the effectiveness of abstinence-only education programs has produced mixed results, with some studies supporting effectiveness and others not supporting effectiveness. Some evaluations indicate that, on average, participants in abstinence-only programs are more likely to abstain from sex than comparison groups but are no more or less likely to engage in risky sexual behavior. However, evaluations using the most effective practices find much weaker positive effects than those that can only approximate these practices. This entry notes that abstinence-only programs often reinforce traditional gender roles and neglect issues faced by sexual minorities. ...