Personality traits predict the quality of intimate relationships, and as a result can be useful additions to assessments of couple functioning. For traits involving social behavior, the affiliation (i.e., warmth, friendliness vs. hostility, quarrelsomeness) and control (i.e., dominance vs. deference, submissiveness) dimensions of the interpersonal circumplex (IPC) are an alternative to the 5-factor model traits of agreeableness and extraversion, given that they may provide a more specific and relevant description of social behavior in the context of couple functioning. The couple context creates an opportunity to supplement commonly used self-reports with informant ratings. Although substantial correlations between self-reports and partner ratings of personality are well-documented, differences between these assessment modalities in levels of affiliation and control have not been examined previously. The present study of 301 middle-aged and older couples addressed this issue by comparing self-reports and spouse ratings, using parallel forms of a measure of the interpersonal circumplex derived from the NEO (Neuroticism-Extraversion-Openness) PI-R (Personality Inventory-Revised). Participants reported lower trait dominance relative to spouses’ ratings, and less trait hostility. For dominance, this discrepancy was evident at all levels of marital quality, but for hostility it was particularly apparent among couples reporting low marital quality. The tendency to self-report less dominance relative to ratings by spouses was stronger among women than men. These discrepancies may be important in couple assessment and intervention.