The personality trait of conscientiousness is an important predictor of health and longevity. The present research examined how conscientiousness, in combination with educational attainment and health-related behaviours, predicted self-reported physical health across adulthood. These relations were investigated in two studies, one using a large, representative sample of Illinois residents (N = 617) and the other using a community sample with a multi-method assessment of conscientiousness (N = 274). Across both studies, structural path analyses provided evidence for a model wherein conscientiousness predicted health, in part, through its relationship to both educational attainment and health-related behaviours. The findings suggest conscientiousness predicts health through a diverse set of mechanisms including, but not limited to, educational attainment and health-related behaviours.