Using a self-regulatory process, individuals act upon their cognitive and emotional representations of health threats to actively manage their health. Leventhal’s common-sense model describes cognitive representations of illness that include perceptions about the identity, timeline, consequences, control and cause of illness. Research has shown that individuals’ illness perceptions predict health behaviours and functional outcomes, particularly when perceptions are specific. Psychometric assessments of illness perceptions need to have the ability to detect specific and idiosyncratic perceptions and emotions; methods include rating scales and patients’ drawings of their illness. Recent randomised trials have demonstrated that interventions can change illness perceptions and improve health outcomes in patient groups, including those with normal test-results, and that family members also benefit from such interventions. These innovations inform clinical applications for improving patient health.