Few studies have tested a broad range of theory-based determinants of injection-related risk and protective behaviors. The current study hypothesize relationships among attitudinal beliefs, normative influences, perceived self-efficacy, intentions, and performing these behaviors consistent with the theory of planned behavior and related models. The conceptual model was tested in a cross-sectional sample of 895 drug injectors recruited from street settings in the southwestern United States and who completed a face-to-face interview. Structural equation modeling results showed intention and self-efficacy most consistently predicted needle sharing and bleaching considering all other model variables. Discussion focuses on the value of using these theoretical concepts to examine needle sharing and other behaviors among injection drug users and their relevance for developing HIV-reduction interventions.