Journal of Urban Health: Bulletin of the New York Academy of Medicine, Vol. 83, No. 3 doi:10.1007/s11524-006-9052-7 * 2006 The New York Academy of Medicine Effectiveness of Respondent-Driven Sampling for Recruiting Drug Users in New York City: Findings from a Pilot Study Abu S. Abdul<Quader, Douglas D. Heckathorn, Courtney McKnight, Heidi Bramson, Chris Nemeth, Keith Sabin, Kathleen Gallagher, and Don C. Des Jarlais ABSTRACT A number of sampling methods are available to recruit drug users and collect HIV risk behavior data. Respondent-driven sampling (RDS) is a modified form of chain-referral sampling with a mathematical system for weighting the sample to compensate for its not having been drawn randomly. It is predicated on the recognition that peers are better able than outreach workers and researchers to locate and recruit other members of a Bhidden^ population. RDS provides a means of evaluating the reliability of the data obtained and also allows inferences about the characteristics of the population from which the sample is drawn. In this paper we present findings from a pilot study conducted to assess the effectiveness of RDS to recruit a large and diversified group of drug users in New York City. Beginning with eight seeds (i.e., initial recruits) we recruited 618 drug users (injecting and non-injecting) in 13 weeks. The data document both cross-gender and cross-race and -ethnic recruitment as well as recruitment across drug-use status. Sample characteristics are similar to the character- istics of the drug users recruited in other studies conducted in New York City. The findings indicate that RDS is an effective sampling method for recruiting diversified drug users to participate in HIV-related behavioral surveys. KEYWORDS Human immunodeficiency virus, Recruitment of drug users, Respondent- driven sampling, Sampling hidden populations. INTRODUCTION AND BACKGROUND In 2005, the Centers for Disease Control and Prevention implemented the National HIV Behavioral Surveillance (NHBS) among injecting drug users (IDUs) in 25 U.S. metropolitan statistical areas (MSAs). Prior to the implementation of NHBS, CDC conducted a pilot study in New York City to assess the effectiveness of respondent- Abdul<Quader, Sabin, and Gallagher are with the Centers for Disease Control and Prevention, Atlanta, USA; Heckathorn is with the Department of Sociology, Cornell University, New York, USA; McKnight, Bramson, and Des Jarlais are with The Baron Edmond de Rothschild Chemical Dependency Institute, Beth Israel Medical Center, New York, USA; Nemeth is with the New York State Department of Health, Albany, USA. Correspondence: Abu S. Abdul<Quader, PhD, Behavioral and Clinical Surveillance Branch, Division of HIV/AIDS Prevention-Surveillance and Epidemiology, National Center for HIV, STD and TB Pre- vention, Centers for Disease Control and Prevention, 1600 Clifton Road, MS E-46, Atlanta, GA 30333, USA. (E-mail: afa3@cdc.gov) 459