Consensually nonmonogamous relationships are those in which all partners explicitly agree that each partner may have romantic or sexual relationships with others (Conley, Ziegler, Moors, Matsick, & Valentine, 2013 ). In this article, research examining the associations between consensual nonmonogamy, psychological well-being, and relationship quality is reviewed. Specifically, three types of consensual nonmonogamy are examined: swinging, open relationships (including sexually open marriage and gay open relationships), and polyamory. Swinging refers to when a couple practices extradyadic sex with members of another couple; open relationships are relationships in which partners agree that they can have extradyadic sex; and polyamory is the practice of, belief in, or willingness to engage in consensual nonmonogamy, typically in long-term and/or loving relationships. General trends in the research reviewed suggest that consensual nonmonogamists have similar psychological well-being and relationship quality as monogamists. Methodological challenges in research on consensual nonmonogamy and directions for future research are discussed.