The trustworthiness of self-reported sexual behavior data has been questioned since Kinsey's pioneering surveys of sexuality in the United States (Kinsey et al., 1948, 1953). In the era of HIV and AIDS, researchers and practitioners have employed a diversity of assessment techniques but they have not escaped the fundamental problem of measurement error. We review the empirical literature produced since Catania et al.'s (1990) review regarding reliability and validity of self-administered and automated questionnaires, face-to-face interviews, telephone interviews, and self-monitoring approaches. We also provide specific recommendations for improving sexual behavior assessment. It is imperative that standardized self-report instruments be developed and used for sexual risk-behavior assessment.