Social networking sites (SNS) are now deeply ingrained in our interpersonal world. Past research has shown various impacts of SNS on intimate relationships, from facilitation of relationship initiation to new sources of conflicts between romantic partners. In two studies, we examined Facebook-related jealousy as a risk factor for the perpetration of intimate partner violence (IPV) in adolescents and young adults. In study 1, 1508 participants completed an online survey assessing Facebook use, Facebook jealousy, and IPV perpetration. Facebook jealousy emerged as a significant mediator of the association between Facebook use and IPV. In study 2, we used a dyadic perspective to investigate the joint contribution of both partners' Facebook jealousy to IPV perpetration. In a sample of 92 youth (46 couples), results showed a significant interaction between own and partner Facebook jealousy. More specifically, own Facebook jealousy was associated with IPV perpetration only at high levels of partner Facebook jealousy. These findings suggest that online behaviors have meaningful implications for offline conflicts and aggression in intimate relationships.