This study examined the role of extradyadic involvement (EDI) in heterosexual dating relationships among young adult females (N = 539). A considerable percentage of participants (36 %) reported that they had engaged in an extradyadic emotional or sexual relationship within the last 2 months. Results from logistic regression analyses supported the general hypothesis that emotional and sexual EDI were both significantly associated with relationship dissolution. These associations remained strong even after controlling for participants' age, relationship duration, and relationship quality. The findings also showed that the strength of the association between acts of emotional or sexual extradyadic behaviors and relationship dissolution was linked to relationship quality, gender of the actor, and type of EDI (emotional vs. sexual). Specifically, compared to participants who reported poor relationship quality, those who reported high relationship quality were more likely to end the partnership if they reported emotional or sexual EDI. Findings suggest that individuals in higher quality relationships appear to have considerably more to lose in their relationship when emotional or sexual EDI occurs. This, in part, may be because the more satisfactory the relationship the more disillusionment one may feel when betrayed by their romantic partner. Overall, the present findings underscore the multifaceted nature of the relationships between EDI and relationship dissolution. We call for more research that rigorously examines what contextual factors influence young adults in dating relationships to dissolve relationships following EDI.