In the current study, respondents were recruited using Respondent Driven Sampling (RDS),an established research method for anonymously recruiting hard-to-reach populations (Heckathorn, 1997, 2002, 2007) such as the New York City methamphetamine user network. This process resulted in the recruitment of 132 eligible participants, starting from (n = 37) RDS “seeds” reached using a Craigslist advertisement. Additional (n = 95) respondents were obtained by referrals via the standard RDS protocol.