To measure self-efficacy with respect to risk behaviors for HIV infection, a set of questionnaire items was developed regarding condom use, drug use with friends, and negotiations with potential sex partners. These items were tested with a sample of Latinos aged 14 to 22 years in two New England cities. A nine-item self-efficacy scale was found to have a high level of internal consistency (Cronbach's alpha = .77). Reliability coefficients were similar for men, women, and both English- and Spanish-speaking respondents. Strong associations with recent performance accomplishments, as specified in Bandura's social cognitive theory, support the construct validity of the scale.