Most studies on the transmission of HIV depend upon self-reports of risky behaviors. This study examines if there is social desirability bias with respect to self-reported condom use behavior, assesses the reliability of a self-reported condom use scale, and validates the self-reported findings with clinical sexually transmitted infection (STI) diagnosis for commercial sex workers (N = 1,383) in the Philippines. The reliability of the condom use scale is .81, and results from confirmatory factor analysis indicate that the data fit the model well. Sex workers who reported using condoms consistently had significantly lower rates of sexually transmitted infections compared to those who never used a condom (t = 7.79, p < .01). It was concluded that no social desirability bias existed with the self-reported condom use scale. Furthermore, the condom use measure was found to have a high level of concurrent validity with STI outcomes.