Infection prevention and control processes in healthcare institutions often rely on healthcare personnel’s compliance with behavioral recommendations. However, knowledge of prevention behaviors is often not sufficient to facilitate sustained compliance with said recommendations. Infection preventionists can use theories of health behavior to explain and change healthcare personnel behavior to increase patient and employee safety. Theories described in this chapter include the health belief model, theory of planned behavior, social cognitive theory, and transtheoretical (or stages of change) model. While each theory is distinct, there are key determinants that are shared across theories and are universally applicable in infection prevention and control. In practice, infection preventionists must first understand the determinants of behavior in their unique population, then plan interventions that address the most salient determinants of behavior within the context of their healthcare setting.