Analyses assessed the degrees to which personality accounts for associations between marital quality and parenting and mediates genetic contributions to these relationships. Participants included 318 male and 544 female same-sex twin pairs from the Twin and Offspring Study in Sweden. All twins completed self-report measures of marital quality and personality (anxiousness, aggression, sociability). Composite measures of parent negativity and warmth were derived from the twins' and their adolescent children's ratings of the twins' disciplinary styles and the emotional tone of the parent-child relationship. Observational ratings of marital quality and parenting were also obtained for a subset of twins. Personality characteristics explained 33% to 42% of the covariance between reported marital quality and parenting and 26% to 28% of the covariance between observed marital quality and parenting. For both sets of analyses, personality accounted for more than half of the genetic contributions to covariance between marital quality and parenting. Results indicate that personality significantly contributes to associations between marital quality and parenting and that personality is an important path through which genetic factors contribute to family relationships.