Substance use is highly prevalent among homeless, street-involved young people. Societal estrangement is often associated with substance use, particularly among this population. The current study utilized a descriptive correlational design to identify four domains of social estrangement: disaffiliation, human capital, identification with homeless culture, and psychological dysfunction. These domains were tested to determine their association with alcohol or drug dependence. Interviews utilizing self-report instruments were conducted with 185 young adults aged 18-23 years of age who were receiving homeless services from a community drop-in center. In this sample, the vast majority reported high levels of alcohol and drug use with more than half being identified as dependent on alcohol and/or drugs. Polysubstance use was highly prevalent and most reported marijuana as their drug of choice. Findings indicate that identification with homeless culture was the most highly predictive domain of social estrangement for both alcohol and drug dependency. Implications for services to this population are discussed. Tables and references (Published Abstract)