This study examined the role of couple similarity in spouses' marital satisfaction and affect. The associations between spousal similarity and relationship measures were examined in a sample of 248 married couples. As hypothesized, greater similarity between partners was associated with higher levels of marital satisfaction and lower levels of negative affect. In particular, similarity on the gendered personality and values domains was more strongly associated with relationship measures, whereas similarity on the attitudes and religiosity domains showed weaker and inconsistent patterns of associations. Finally, profile-based similarity tended to be a stronger and more consistent correlate of relationship measures than difference score-based similarity. The implications of these findings for processes underlying intimate relationships are discussed.