By understanding an individual’s dispositional thoughts, feelings, and behaviours, one can gain valuable insight into whether that person will live a healthier and longer life. Personality dimensions consistently predict who is more likely to experience better health outcomes across the lifespan and for multiple reasons. The current entry describes some of the central pathways by which personality impacts health, and how these mechanisms play out in daily life. Future directions for research are charted, focussing on how to better integrate relationship variables into personality and health models. In so doing, this entry helps explain why our personalities, and the personalities of those around us, play such a central role in predicting health and well-being outcomes.