Although intimate partner violence (IPV) is often conceptualized as occurring unilaterally, reciprocal or bidirectional violence is actually the most prevalent form of IPV. The current study assessed physical IPV experiences in couples and evaluated risk and protective factors that may be differentially associated with reciprocal and nonreciprocal IPV concurrently and over time. As part of a multi-wave longitudinal study, women and men reported on the frequency of their IPV perpetration and victimization three times across the transition to parenthood. Participants also reported on risk factors related to personal adjustment, psychosocial resources, attitudes toward gender role egalitarianism, and sociodemographic characteristics at each wave. Participants were classified into one of four IPV groups (reciprocal violence, male perpetrators only, female perpetrators only, and no violence) based on their self-report and based on a combined report, which incorporated both partners' reports of IPV for a maximum estimate of violence. Women and men were analyzed separately, as both can be perpetrators and/or victims of IPV. Cross-sectional analyses using self-reported IPV data indicated that IPV groups were most consistently distinguished by their levels of couple satisfaction, across gender; psychological distress also appeared to differentiate IPV groups, although somewhat less consistently. When combined reports of IPV were used, sociodemographic risk markers (i.e., age, income, and education) in addition to couple functioning were among the most robust factors differentiating IPV groups concurrently, across gender. In longitudinal analyses, sociodemographic vulnerabilities were again among the most consistent factors differentiating subsequent IPV groups over time. Several gender differences were also found, suggesting that different risk factors (e.g., women's social support and men's emotion regulation abilities) may need to be targeted in interventions to identify, prevent, and treat IPV among women and men.