“…In order to examine the relationship between residence status, stability, and more serious forms of illicit drug use, we chose to exclude alcohol and marijuana from our analyses given that both of substances are readily available and commonly used within the general population of adolescents and young adults. In addition, we chose to examine recent use of a subset of drugs called "club drugs" given that club drug use appears to be highly associated with HIV risk-related sexual behaviors (Halkitis et al, 2001;Koblin et al, 2003;Reback, 1997;Reback et al, 2004;Stall and Ostrow, 1989;Thiede et al, 2003;Weber et al, 2003), and thus is believed to be fueling recent waves of HIV infection among MSM (Eichenthal, 2001;Guss, 2000;Halkitis et al, 2005;Halkitis et al, 2001;Halkitis et al, 2003;Patterson and Semple, 2003;Reback et al;. For the purpose of this study, club drugs were defined to include: cocaine, crystal/methamphetamine, ecstasy, poppers, GHB, Ketamine, and "other forms of speed.…”