The common sense model of illness self-regulation outlines the dynamic processes by which individuals perceive, interpret, respond, and adjust, psychologically and behaviorally, to health threats and illness-related information. An extended version of the model is presented, which formally operationalizes existing processes in the model and specifies additional constructs and processes to explain how lay perceptions of health threats and illnesses impact coping responses and health-related outcomes. The extended model provides detail on: (a) the mediating process by which individuals’ illness representations relate to illness outcomes through adoption of coping strategies; (b) representations of health threats and illnesses as schematically organized and activated by presentation of health-threatening stimuli; (c) behavioral and treatment beliefs as determinants of coping responses and illness outcomes independent of illness representations; and (d) effects of salient moderators (e.g., optimism, perfectionism, trait negative affectivity, emotional representations) of relations between cognitive representations, coping responses, and illness outcomes. The extended model is intended to set an agenda for future research that addresses knowledge gaps regarding how individuals represent and cope with illnesses and health threats, and augments the evidence base that may inform effective and optimally-efficient illness-management interventions. We also identify the specific kinds of research required to provide robust evidence for the revised model propositions. We call for research paradigms that employ incipient illness samples, utilize designs that better capture dynamic processes in the model such as cross-lagged panel and intervention designs, and adopt illness-specific measures of coping behaviors and self-management actions rather than reliance on generic instruments.