In this study, the association was explored between the number of sexual partners individuals had in their lifetimes and martial outcomes. The research objective was to test whether the number of sexual partners was associated with sexual quality, communication, relationship satisfaction, and relationship stability, while controlling for relationship length, education, race, income, age, and religiosity, using the two competing theories of sexual compatibility and sexual restraint. The results, with a sample of 2,654 married individuals, indicated that the number of sexual partners was associated with lower levels of sexual quality, communication, and relationship stability, providing support for the sexual restraint theory. Gender was not significantly associated with the patterns in the model but age cohorts did have different patterns.