Most agencies were in the Sydney, Australia, metropolitan area. Heroin was the drug most used by respondents (94.8 percent) and/or the drug for which they were seeking treatment. The typical respondent was likely to be male, single, aged in the 20's, a high school dropout, and unemployed. The mean ages of first and regular heroin use were 18.7 and 20.1, respectively. The last time heroin had been obtained, it had usually been purchased for cash from a full-time dealer. The most usual sources of income to purchase drugs were drug selling (33 percent), social security (28.3 percent), employment (27.6 percent), and property crime (25.2 percent). Prior to treatment, 64 percent reported selling drugs daily or frequently, usually to people they knew or who had been referred to them. When asked about their historical involvement in crime, respondents reported being mostly involved in drug selling (69.3 percent), break/enter and steal (30.7 percent), and fraud (22.8 percent). More respondents had sold drugs, stolen a car, or shoplifted prior to or simultaneously with their first use of heroin than after; while for other crimes, the first offense was more likely to have occurred after first use. In most instances, regular involvement in drug selling occurred before onset of regular heroin use, while the opposite was true for regular involvement in property crime. However, 64 percent of respondents considered all their crimes to be heroin related. 44 tables, 3 appendixes, and 28 references.