The purpose of this paper is to identify characteristics of heroin sniffers likely to shift to injection by evaluating the street addict role theory as an informing theoretical framework to explain transition from heroin sniffing to injection. A nested case-control research design was used to identify 142 heroin sniffers who never had injected a drug (controls) and 146 recently transitioned injection drug users (cases) from a larger study of 600 African-American, Hispanic, and non-Hispanic white men and women who were street recruited from multiple communities known for high drug use. Univariate and multivariate logistic regression analyses were conducted to test the proposed hypotheses derived from the street addict role theory. Our findings partially support the utility of the street addict role perspective as an explanatory framework for understanding the role played by sociocultural factors in the transition to injection. This perspective can help contextualize this HIV-related behavior within the high risk social environment of heroin users. The development of effective prevention strategies for this group should be guided by a comprehensive understanding of the social environment where HIV-related risk behaviors occur.