This objective of this dissertation is to establish the relevance of imagination in understanding health behavior, particularly the phenomenon of patient nonadherence. This prevalent phenomenon refers to situations in which patients fail to follow through on medical advice. Finding a solution to patient nonadherence in the U.S. context is of great interest, due to nonadherence significantly contributing to rising healthcare expenditures, higher mortality rates, and more frequent hospital stays. Health psychology is the principal disciplinary field within which the search for solutions occurs. There are many theoretical frameworks within health psychology that aim to adequately describe and/or explain the nature of nonadherent behavior. However, the vast majority of these frameworks overestimate the importance of cognitive factors (e.g., beliefs, background knowledge, consciously articulated desires, etc.) while downplaying the importance of experiential and/or emotional factors. The one theory that does account for the latter features of health behavior, the Common Sense Model (CSM) of Illness Representations, ultimately succumbs to the asymmetric focus on cognitive factors. My central argument is that reorganizing the CSM in terms of imagination has the potential to both reorient the empirical study of nonadherence as well as the patient-provider relationships.