Cultural sensitivity has been identified as an important component of assessment and intervention for HIV risk. Recognizing cultural norms is important for selecting methods for assessment and intervention. The behavioral HIV literature in Thailand is reviewed to illustrate the importance of the localization of cultural norms and practices, the often fragmented or mediated character of broad social dynamics, and subtleties of drawing cross-cultural inferences. We also discuss the implications of cultural norms for selecting research methods and highlight the importance of participatory research approaches for adequately capturing and incorporating cultural elements in the design of assessments and interventions.