There is substantial evidence that married people fare better than their unmarried peers on many life outcome variables. The authors asked whether self-selection might partially explain these benefits through genetic influences on personality contributing to propensity to marry. Using a population-based sample of 4,225 women and 2,869 men that included 2,527 complete twin pairs, the authors investigated the phenotypic associations between personality and propensity to marry, the heritability of propensity to marry, and the extent of genetic influence on the link between personality and propensity to marry. The results suggest that propensity to marry is heritable and that the phenotypic link between personality and propensity to marry is genetically influenced.