Sexual prejudice is an important threat to the physical and mental well-being of lesbians, gay men, and bisexual people. Therefore, we reviewed the effectiveness of interventions designed to reduce such prejudice. A study-space analysis was performed on published and unpublished papers from all over the world to identify well-studied and underexplored issues. Most studies were conducted with North American undergraduates and were educational in nature. Dissertations were often innovative and well designed but were rarely published. We then performed meta-analyses on sets of comparable studies. Education, contact with gay people, and combining contact with education had a medium-size effect on several measures of sexual prejudice. The manipulation of social norms was effective in reducing antigay behavior. Other promising interventions, such as the use of entertainment media to promote tolerance, need further investigation. More research is also needed on populations other than American students, particularly groups who may have higher levels of sexual prejudice.