In addition to individual-level socioeconomic and psychological factors, the neighborhood environment has been found to be related to medication nonadherence, particularly among low-income, minority populations managing a chronic disease. In this article, we synthesize the relevant literature on how neighborhood factors contribute to engagement in health behaviors and reasons for medication nonadherence among this population. We propose a theoretical framework for understanding the mediating and moderating mechanisms whereby the neighborhood environment may impact medication nonadherence among individuals most at risk for adverse disease outcomes. Guided by this model, we provide recommendations for future research, practice, and policy.