1. Shelley N. Facente is with the School of Public Health, University of California Berkeley. Jamie L. Humphrey, Christopher Akiba, Sheila V. Patel, Lynn D. Wenger, Terry Morris, Alex H. Kral, and Barrot H. Lambdin are with RTI International, Berkeley. Hansel Tookes is with the University of Miami, Miami, FL. Ricky N. Bluthenthal is with University of Southern California, Los Angeles. Paul LaKosky and Stephanie Prohaska are with the North American Syringe Exchange Network, Tacoma, WA.