Dominant gender roles contribute to the risk of contracting HIV, for that reason the integration of social norms regarding gender into HIV prevention interventions has been urged. This study aims to adapt and develop an intervention to facilitate the transformation of social norms related to gender and sexual practices in Puerto Rican men. The intervention aims to transform social norms related to gender and sexuality in community bars using the Popular Opinion Leaders Model. After being selected, opinion leaders disseminate messages that stress the importance of equitable relationships between men and women for HIV prevention. The first phase of this intervention is discussed in this article. This phase includes a process of rapid ethnography to identify community settings in which we could develop the intervention and allow us to understand the culture of these community bars. From ethnographic observations we: developed a security protocol, developed a profile of the culture of these bars, chose the bars that participate in the two study conditions, and adapted the intervention instruments to respond to the particularities of our participants.