The authors' objective was to determine the association between the 'big-five' personality traits and mental and physical disorders among adults in the United States. The Midlife Development in the United States Survey, a nationally representative sample of 3032 adults ages 25-74, was used to determine the association between the five-factor traits of personality and common mental and physical disorders. Findings are consistent with and extend previous results showing that conscientiousness is associated with significantly reduced likelihood of a wide range of mental and physical disorders among adults in the general population, and inversely that neuroticism is associated with increased rates. Among adults with physical illnesses, associations were found between personality and likelihood of physical limitations, especially conscientiousness. These findings provide a framework upon which research on complex causal processes may proceed. Thus future research attention might profitably be directed to conscientiousness-relevant processes, such as adherence to health and treatment recommendations and internalization of healthy societal norms for sensible health-related behavior.