Two studies were conducted to examine the relations between both partners' personality and marital quality in married or cohabiting heterosexual couples. In Study 1 (N = 1380, or 690 couples), personality was assessed by means of the Dutch Personality Questionnaire, whereas in Study 2 (N = 564, or 282 couples) personality was assessed by means of the Five-Factor Personality Inventory. We expected neuroticism to relate negatively, and extraversion positively, to marital quality. Furthermore, we expected that spouses would only marginally resemble each other with regard to personality, and that differences in personality would not affect marital quality, when controlling for the individual's levels of personality. All expectations were confirmed. Copyright © 2005 John Wiley & Sons, Ltd.