In conducting ethnographic research, it is important that fieldworkers have ethical guidelines to provide direction concerning ethical standards, professional conduct, and methods of obtaining high-quality data. In this chapter, the authors address issues that they faced in developing guidelines for ethnographic fieldwork on sexual behavior among Latino men who have sex with men (MSM). Ethnographic observations were conducted as part of a larger study concerning contextual influences on sexual risk among Brazilian, Colombian, and Dominican gay men in the New York City area. Gay-identified Latino fieldworkers carried out participant observation in venues where Latino men went to socialize and to find sex partners. Existing guidelines from professional organizations did not adequately address the unique and special conditions that these fieldworkers faced. Therefore, the authors set out to create their own set of guidelines that prohibited sex and drinking between researchers and their informants. This chapter also compares the different ethical guidelines developed by the two leading psychological and anthropological organizations, the American Psychological Association and the American Anthropological Association, and observes greater ethical flexibility among anthropologists.