Supporters argue that the absence of effective methods of eliminating intravenous drug abuse points to the need to help addicts inject drugs more safely. In contrast, opponents say that needle exchanges will encourage drug use and send the wrong message at a time when the nation appears increasingly concerned about the impact of illicit substance abuse. The 400 participants in the New York City program will carry an identification card allowing them to possess needles. The pilot project will use surveys, self-reports, and serologic analysis of returned equipment to determine whether participants stay in the program; go into treatment; and modify their drug use, equipment sharing, and sexual behavior. The Portland program is broader and is awaiting a liability insurance policy to get under way. The project will examine four cohorts to assess whether the program reduces the spread of HIV and whether it encourages intravenous drug use in people not previously practicing such behavior.