How common is consensual nonmonogamy?
Executive summary
Consensual nonmonogamy (CNM) is neither vanishingly rare nor the default: most rigorous estimates place the share of adults currently practicing CNM in the low single digits, while lifetime or “ever” measures vary widely—some studies of single people report rates above 20 percent, but those figures depend heavily on sampling and definitions [1] [2] [3]. Methodological choices—whether the sample is all adults, only people in relationships, or only single people, and how CNM is defined—drive most disagreements about how common CNM really is [4] [5] [6].
1. Current vs. lifetime prevalence: two different questions, two different answers
Careful population surveys that ask whether someone is presently in an open relationship or otherwise practicing CNM produce modest estimates: representative U.S. data put current engagement at roughly 2–5 percent of adults (2.6% in one nationally representative survey, or about 4% of people currently in relationships) and similar 4% estimates have appeared in other studies [5] [6]. By contrast, surveys that ask whether a person has ever engaged in CNM—or that sample only single adults—produce much higher figures: Haupert and colleagues’ analyses of two U.S. quota samples of single Americans found that about one in five single people reported having engaged in CNM at some point, a result that has been widely publicized and sometimes overstated as applying to all Americans [2] [3] [4].
2. Why measurement and sample design matter
Differences between “ever” and “current” measures, whether the sample is probability-based or quota-based, and how broadly researchers define CNM (swinging, open relationships, polyamory, casual consensual non-monogamy) explain much of the variance across studies [4] [7] [6]. Critics note that some high “1-in-5” headlines come from studies of single people and may conflate casual sexual arrangements with sustained CNM relationships; other surveys like Match.com’s tracking of unmarried Americans or academic reviews use broader questions and thus report higher lifetime rates [4] [8] [6].
3. A conservative synthesis: what the peer-reviewed reviews say
Recent narrative and systematic reviews conclude that a defensible conservative estimate is that a minority of adults—around 4–5 percent—are actively in some form of CNM at a given time in North America, while lifetime exposure (ever engaged) likely ranges higher—estimates across studies and contexts cluster between low teens and low twenties percent depending on definitions and populations sampled [1] [6] [2]. Reviews also emphasize that relationship quality and psychological well‑being among consensually nonmonogamous people are comparable to monogamous people in many studies, underscoring that prevalence is decoupled from value judgments about outcomes [1] [7].
4. Who practices CNM — patterns and caveats
Available research indicates CNM is practiced across ages, races, education and income levels, but with some consistent correlates: men and sexual minorities report higher rates, and LGBTQ+ communities are overrepresented among CNM practitioners in several studies [9] [4] [10]. Researchers caution that stigma and concealment mean some people will underreport CNM, while social desirability in certain subgroups or sampling frames can inflate estimates—both biases operate in different directions depending on survey design [11] [12].
5. What to take away
CNM is not mainstream in the sense of being practiced by the majority, but it is also not an extreme marginality confined to a tiny subculture: a few percent of adults actively practice CNM at any given time, and a substantially larger share—varying by study and definition—report having tried it at some point in life, especially when single populations are sampled [5] [2] [1]. The bottom line: claims like “1 in 5 Americans” reflect particular samples and question wordings and should not be treated as a universal population prevalence without those caveats [4] [3].