In this study of 125 older couples married for an average of 34 years, multilevel models were computed to simultaneously examine intra-couple personality trait averages and between-spouse trait similarity as predictors of marital satisfaction. Our findings suggest that higher intra-couple levels of extraversion predict marital satisfaction, both husbands and wives. In addition, between-spouse similarity in openness to experience appears associated with higher levels of marital satisfaction as reported by husbands; concomitantly, between-spouse similarity in agreeableness predicts wives' marital satisfaction. With respect to openness (husbands) and agreeableness (wives), it did not matter which spouse within couples reported higher or lower trait levels. The most notable finding to emerge from this study is that neuroticism is not associated with marital satisfaction, neither husbands nor wives. This result stands in contrast to previously reported findings--the vast majority of prior research conducted with dating and newlywed couples. Conflicting results may reflect the degree to which neuroticism determines divorce within the first years of married life, adaptation to the foibles of one's spouse over time, overreliance on younger samples in marriage and family research, or some combination of these alternate explanations.