Although there is some evidence that relationship-level factors influence sexual behavior, they have received far less attention than individual-level factors as potential correlates of condom use. This study surveyed 210 undergraduate men and women to examine the association between relationship characteristics and condom use. Higher levels of love, longer relationships and more serious and committed relationships were individually associated with less condom use. In a multiple logistic regression model controlling for HIV/sexually transmitted disease (STD) risk perception and contraceptive method, relationship length was the only relationship factor that independently predicted condom use (OR = .91; 95% CI = .84-.99). Use of a hormonal contraceptive method was negatively associated with condom use in the multivariate model (OR = .12; 95% CI = .06-.27), and mediated the association between relationship factors and condom use. Study results suggest that HIV/STD prevention interventions may be improved by addressing relationship characteristics, particularly the length of a dating relationship.