We report on psychometric properties of a new questionnaire to study long-term strategies, practices and tactics that may help injection drug users (IDUs) avoid infection with HIV and hepatitis C. Sixty-two long-term IDUs were interviewed in New York City in 2009. Five scales based on a total of 47 items were formed covering the following domains: stigma avoidance, withdrawal prevention, homeless safety, embedding safety within a network of users, and access to resources/social support. All scales (α ≥ .79) except one (α = .61) were highly internally consistent. Seven single-item measures related to drug use reduction and injection practices were also analyzed. All variables were classified as either belonging to a group of symbiotic processes that are not directly focused upon disease prevention but nonetheless lead to risk reduction indirectly or as variables describing prevention tactics in risky situations. Symbiotic processes can be conceived of as unintentional facilitators of safe behaviors. Associations among variables offer suggestions for potential interventions. These Staying Safe variables can be used as predictors of risk behaviors and/or biological outcomes.