Contemporary family research studies have devoted surprisingly little effort to elucidating the interplay between adults' individual adjustment and the dynamics of their coparental relationship. In this study, we assessed two particularly relevant “trait” variables, parental flexibility and self-control, and traced links between these characteristics and the nature of the coparents' interactions together with their infants. It was hypothesized that parental flexibility and self-control would not only explain significant variance in coparenting quality, but also act as moderators attenuating anticipated relationships between marital functioning and coparental process. Participants were 50 heterosexual, married couples and their 12-month-old infants. Multiple regression analyses indicated that even after controlling for marital quality, paternal flexibility and maternal self-control continued to make independent contributions to coparenting harmony. As anticipated, paternal flexibility attenuated the association between marital quality and coparenting negativity. Contrary to predictions, maternal flexibility and self-control did not dampen, but actually heightened the extent to which coparenting harmony declined in the face of lower marital quality.