“…Shooting galleries have been widely studied as HIV risk environments for people who inject drugs (Friedman & Aral, 2001; Klein & Levy, 2003; Rhodes, 2002; Rhodes et al, 2005), crack houses as risk environments for unsafe sex and for risk reduction efforts (Inciardi, 1996; Maher, 1997; Ross et al, 1999; Sterk, 1999, 2000; Williams, 1992), brothels for sex workers and others (Deren et al, 1996; Remple et al, 2007), and bathhouses, public cruising areas and circuit parties as environments conducive to drug use and high-risk sex among gay men (Binson et al, 2001; Choi et al, 2004; Ghaziani & Cook, 2005; Grierson, Smith, & von Doussa, 2008; Ostrow & Stall, 2008; Weidel, Provencio-Vasquez, & Grossman, 2008; Wohlfeiler & Potterat, 2005). This article discusses group sex events—defined as events at which some people have sex with more than one partner—as risk environments, with a particular focus on group sex events where people who take heroin, cocaine or crack by non-injection routes of administration take part and where the event is not primarily LGBT-identified, at a classic crack house, nor in a brothel.…”