We conducted a meta-analysis of randomized controlled trials (RCTs) to evaluate behavioral HIV risk reduction interventions targeting people who inject drugs. We included 37 RCTs evaluating 49 independent HIV risk reduction interventions with 10,190 participants. Compared to controls, intervention participants reduced injection drug use (IDU) and non-IDU, increased drug treatment entry, increased condom use, and decreased trading sex for drugs. Interventions were more successful at reducing IDU when participants were non-Caucasians, when content focused equivalently on drug-related and sex-related risks, and when content included interpersonal skills training specific for safer needle use. Condom use outcomes improved when two intervention facilitators were used instead of one. IDU outcomes did not decay, but condom use outcomes did. Behavioral interventions reduce risk behaviors among people who inject drugs, especially when interventions target both drug risk and sexual risk behaviors, and when they include certain behavioral skills components. Implications for future interventions are presented.