This document summarizes the work of PreventionWorks!, a needle exchange program in Washington DC. A team of Georgetown medical students worked with PreventionWorks! to reduce HIV/AIDS and other diseases among injection drug users. PreventionWorks! operates a mobile van that provides clean needles in exchange for used ones, as well as medical referrals and supplies. It aims to reduce disease transmission through harm reduction services. The program has exchanged over 330,000 needles since 1998. A typical day involves the van stopping in areas with high drug use and infection rates to exchange needles and provide other assistance.