DescriptionIn the years after the onset of the AIDS pandemic, New York State outlawed sexual activity in commercial venues, leading to the gradual closure of most of the bathhouses, sex clubs, and adult theaters where gay men had been having sex in New York City (NYC) for decades. Indirectly, these restrictive interventions led to the proliferation of underground sex clubs, which have become the main institution for gay group sex in NYC today. This study wants to understand what type of social and sexual practices take shape in the context of clandestine sex clubs. To do so, this dissertation provides a history of gay cruising, a review of the empirical literature on gay public sex, ethnographic data describing the organization of NYC's private sex clubs and their norms of interaction, and data from in-depth interviews with sex-party-goers. Past research on gay cruising emphasized its anonymous and impersonal aspects, but this study found private sex clubs to be the site of what I call collective intimacy. By practicing collective intimacy, sex-party-goers break the traditional boundaries between sex, intimacy, and sociability. The organization and environment of private sex clubs foster collective intimacy by putting groups of gay men together in places where they must share close physical intimacy and where repeat encounters are likely. Instead of disrupting sexual networks, restrictive interventions had instead created a context of clandestinity in which sex-party-goers are more closely connected to one another. Practices of collective intimacy are likely to be present in the future because they answer a growing need for sexual recreation and for flexible intimate and social relations.