The cycle of use is described in several ways; one focuses on four steps in terms of social functioning: experimenting, social recreational using, involved using, and dysfunctional abusing. Besides access to the drug, circumstances for onset include psychological, demographic, cultural, economic, and sociological factors. Until recently, initial heroin users had previously experimented with marijuana. Various studies suggest that the lower the age of onset of heroin use, the longer it is likely to continue. A substantial proportion of heroin users are clearly able to function in a regular work situation. Heroin users have diverse relationships with criminal activities. The likelihood of arrest and the severity of sentencing varies considerably from one community to another. The five basic reasons for temporary or permanent abstinence for heroin use include external circumstances, relationships jeopardized by continued use, weariness, personality and insight, and physical problems. Case study and 51 references