The common sense model of illness self-regulation outlines the dynamic processes by which individuals perceive, interpret, and respond to health threats and illness-related information. An extended version of the model is proposed, which specifies additional constructs and processes to explain how lay perceptions of health threats 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 procedures; (b) how illness representations are activated by presentation of health-threatening stimuli; (c) behavioral and treatment beliefs as determinants of coping procedures and illness outcomes alongside illness representations; and (d) effects of moderators of relations between cognitive representations, coping procedures, and illness outcomes. The extended model sets an agenda for future research that addresses knowledge gaps regarding how individuals represent and cope with health threats, and may inform effective illness-management interventions. We identify the kinds of research required to provide robust evidence for the extended model propositions. We call for research that employs incipient illness samples, utilizes designs that capture dynamic processes in the model such as cross-lagged panel and intervention designs, and adopts illness-specific measures of coping procedures rather than relying on generic instruments.