Using qualitative interviews conducted in 1999, we examine awareness and use of drug user treatment and social service referrals, medical care, and HIV testing provided by needle exchange programs (NEPs) among injectors who use NEPs (N = 26) and injectors who get their syringes from other sources (N = 20). A four-category typology of NEP service knowledge and use emerges from these interviews: "Active involvement" - use of services; "Steppingstone" - no use of services but knowledge that specific services are available; "Vague awareness" - nonspecific knowledge of service availability; and "Un...