The aim of this project was to conduct an initial evaluation among sexually transmitted disease (STD) patients of the psychometric properties of two instruments: the National Institute of Mental Health (NIMH) multisite condom use self-efficacy scale and the NIMH multisite condom use outcome expectancy scale. The condom use self-efficacy scale was designed to measure one's degree of confidence in various aspects of condom use, whereas the outcome expectancy scale was designed to measure one's belief about the consequences of using condoms. Using a sample of 641 patients from five geographically diverse STD clinics in the eastern United States, initial reliability coefficients were computed. The alpha coefficient for the self-efficacy scale was .91 and for the outcome expectancy scale .88, indicating high internal consistency for both scales. Both scales were analyzed using common factor analytic procedures. Five factors emerged from the analysis of the self-efficacy scale and six factors from the analysis of the outcome expectancy scale. Reliability coefficients for the individual factors ranged from .76 to .86. Construct validity of each scale was assessed by hypothesis testing. As predicted, participants with higher levels of self-efficacy and more positive outcome expectancies were more likely to use condoms.