Sexual promiscuity is a known risk factor for unprotected sex. A related variable, emotional promiscuity, has conceptual relevance but has yet to be studied with respect to unprotected sex. Data from four studies (total N = 908) indicated that both sexual promiscuity and emotional promiscuity were associated with womens' reports of unprotected sex. Independent of those contributions, the interaction between sexual promiscuity and emotional promiscuity was also significant for women: Scoring high on both variables was associated with the highest number of unprotected partners. This synergistic interaction emerged whether the question about number of unprotected partners referred to the past year or lifetime total. The interaction held up even after controlling for other relevant factors (lifetime partners, romantic beliefs, and attachment styles). In sum, among sexually active women, the susceptibility to falling in love puts them at risk for unprotected sex. Our discussion addresses possible mechanisms and why the key interaction only emerged in women.