The user group was compared with the nonuser group. For 78.2 percent of heroin users, property crime was their main source of income. For nonusers, 64.4 percent reported so-called licit sources (job and social security) as their main source of income. Users also generated more income from property crime and committed significantly more burglaries, armed robberies and frauds than nonusers in the specified period prior to arrest. As consumption and expenditure increased, so did the amounts of income generated by property crime. The involvement of users in particular types of property crime (armed robbery and break-and-enter) also increased with drug consumption. These findings suggest that prerelease and postrelease drug treatment programs are important in reducing criminal behavior. This implies the identification of drug abusers prior to sentencing. 41 tables, 77-item bibliography.