Polyamory

Polyamory means more than one romantic relationship at a time, with everyone's knowledge and consent. The word dates from 1990 to 1992. In a 2021 study of 3,438 single US adults, 10.7% had engaged in it at some point. Research compares primary and secondary partners, and since 2020 a few US cities and towns have recognized multi-partner domestic partnerships.

Updated October 6, 2026

Means

More than one romantic relationship at a time, with everyone's knowledge

First seen

'Poly-amorous' in Morning Glory Zell-Ravenheart's 'A Bouquet of Lovers', Green Egg, Beltane (May) 1990, reportedly without the noun; 'polyamory' proposed for the Usenet group alt.polyamory, founded by Jennifer Wesp on May 29, 1992; added to the OED in 2006 according to a 2007 report; Merriam-Webster dates it to 1992

Related terms

ENM (ethical non-monogamy), Open relationship, Casual dating, DTR (define the relationship), Situationship

In Swedish

Polyamori

Polyamory is having more than one romantic relationship at a time, with everyone involved knowing about the others. The noun is about 34 years old. A Usenet group proposed it in 1992, two years after a magazine article reportedly used the hyphenated form “poly-amorous”. The rest of this page covers where the word comes from, what the studies compared, how many people say they do it, and which US cities have written it into local law.

What is polyamory? Meaning, and where the word comes from

The Usenet group where the word took hold defined it in its FAQ: “Polyamory means ‘loving more than one’. This love may be sexual, emotional, spiritual, or any combination thereof, according to the desires and agreements of the individuals involved” (alt.polyamory FAQ, 1997).

Merriam-Webster and, per the 2007 report above, the OED both credit 1992. Researchers file polyamory under consensual non-monogamy, or CNM, the research name for what dating profiles call ENM.

Polyamory vs open relationship, ENM and polygamy

An open relationship usually opens sex: one couple stays the couple and agrees that sex with others is allowed. Polyamory opens love, meaning more than one relationship that matters, with everyone aware of the others. Our rule of thumb, borrowed from the open-relationship page: count the relationships that matter to the people in them. One couple with agreed outside sex is an open relationship; a second relationship that matters to someone is nearer polyamory.

ENM, ethical non-monogamy, is the umbrella over both, and over swinging and relationship anarchy too; the types of ENM table sets them side by side.

Polygamy is about marriage, polyamory about relationships. The city ordinances further down create domestic partnerships and rules against discrimination, not marriages. In Massachusetts, where the earliest of them passed, state law says that, apart from the exceptions it lists, a marriage contracted while either party “has a former wife or husband living” “shall be void” (Massachusetts General Laws, c. 207, s. 4).

On The Student Room, a UK student forum, a thread titled “Explaining polyamory and bisexuality to people” was started on June 20, 2025 and has about 21 replies. Its opening poster asked: “I mean, why polyamory immediately means an open relationship? It doesn’t have to be and it better not be” (The Student Room, June 2025). On Mumsnet, a British parenting forum, a “Polyamory” thread in the chat section was started on October 6, 2018 and has about 12 replies. A reply told the poster: “That’s ‘open relationship’ territory. Polyamory is more usually used when you have a multiway relationship as a group of three or more” (Mumsnet, October 2018).

How polyamory works: hierarchical, kitchen-table, solo poly and other terms

Polyamorous people have built a vocabulary for who ranks where and who meets whom. The last column gives the earliest dated source we found; where we found none, the definition is ours.

Balzarini and colleagues defined a primary relationship as one “between two partners who typically share a household (live together) and finances, who are married (if marriage is desired), and/or who have or are raising children together (if children are desired)”. In their convenience sample of 1,308 self-identified polyamorous people, recruited online from December 2012 to January 2013, 72.21% shared a household with a primary partner and almost none with a secondary (Balzarini et al., 2017). Our reading of the table above: most of these terms describe who knows whom and who lives with whom.

How many people are polyamorous?

The figures here are about polyamory, apart from two YouGov 2025 items that merge it with open relationships (explained below the table). They measure different things: having done it, wanting to, knowing someone who has, and calling it wrong.

The 2021 figures come from single adults, while YouGov’s 2025 poll was not limited to singles. YouGov also merged polyamorous and open relationships into one item for both the “ever” and the “would consider” questions, so its 9% is an upper limit for polyamory alone in that sample.

Both US morality polls in the table found disapproval the larger answer. The UK one, the only UK figure we found, defines the word by sex: “there is a large group (47%) who even say that polyamory (having multiple consensual sexual relationships at once) is morally wrong” (YouGov UK, 2015). That gloss sits nearer what this page calls an open relationship.

We found no UK prevalence figure, and no Canadian national one: Statistics Canada did not track polyamory as of 2017 (Vanier Institute, 2017). Wider ENM numbers are tabled under how common ENM is.

One app figure, labeled as company data: Feeld added Constellation on June 20, 2024, letting members “link their profiles with up to 5 other partners”. The same release claimed “a staggering 966% growth in Members who express polyamory or ethical non-monogamy as a desire” since its 2017 Paired Partner feature; that is Feeld’s own figure, and it gives no base (Feeld, 2024). More on the app is on our Feeld page.

Is polyamory healthy? What research says about primary and secondary partners

We found no study that answers this for any one person. The studies below mostly used convenience samples, people who chose to take an online survey.

In the 2017 study of 1,308 by Balzarini and colleagues, “Participants reported less stigma as well as more investment, satisfaction, commitment and greater communication about the relationship with primary compared to secondary relationships, but a greater proportion of time on sexual activity with secondary compared to primary relationships.” Primary relationships had lasted 8 years and 4 months on average, secondary ones 2 years and 4 months (Balzarini et al., 2017). Our reading: the secondary relationships were also much newer, and averages alone cannot tell rank apart from relationship length.

In a study published online in December 2015, Mogilski and colleagues compared 123 people in monogamous relationships with 76 in CNM ones. The CNM participants “reported higher overall relationship satisfaction with primary compared to secondary partners and considered their primary partner to be more desirable as a long-term mate than their secondary partner.” The monogamous group “performed more mate retention behaviors”, the study’s term; in plain words, efforts to keep a partner (Mogilski et al., 2017).

A 2019 study led by Mogilski, with 529 monogamous and 159 CNM participants, “replicated previous research showing that monogamous individuals mate guard more than CNM individuals, who mate guard their primary versus secondary partner more frequently.” Compersion appears in the study’s title, not in the lines we quote (Mogilski et al., 2019).

Conley and colleagues, in 2018, looked at sexual satisfaction. The abstract says “monogamous people reported slightly lower sexual satisfaction and lower orgasm rates than those who are CNM”, then: “swingers consistently reported higher sexual satisfaction than monogamous individuals, whereas those in open relationships had equivalent levels of satisfaction to those in monogamous relationships. Relationship satisfaction did not differ between CNM and monogamous groups.” The abstract does not single out polyamorous people as a group of their own (Conley et al., 2018).

A 2015 review by Rubel and Bogaert summed up the research so far: “General trends in the research reviewed suggest that consensual nonmonogamists have similar psychological well-being and relationship quality as monogamists” (Rubel & Bogaert, 2015). Similar, on the measures used, is as far as that goes.

Research on the agreements partners make, by Hoff and colleagues and by Vilkin and Davila, is on the open-relationship page.

Is polyamory legal? Domestic partnerships and city laws in the US

None of the laws below is about marriage. Since 2020, a few Massachusetts municipalities have recognized domestic partnerships of more than two people, and cities including Oakland and Portland have banned discrimination based on family or relationship structure. Rows marked “reported” are ones we could confirm only secondhand.

Several of the sources are press releases from PLAC, a project of the Chosen Family Law Center and Harvard Law School’s LGBTQ+ Advocacy Clinic, by its own description (PLAC, 2023). The Massachusetts Attorney General’s decision approving Arlington’s bylaw in December 2021 said it does not redefine marriage and that “polygamy is illegal in the Commonwealth” (reported by Massachusetts Lawyers Weekly via The Daily Record, 2022).

On Mumsnet, a thread titled “Polyamorous / Ethically Non-Monogamous Parents” was started on December 26, 2018 and has about 104 replies. The opening poster, on December 27, 2018, drew the line between the two: “Polyamory and polygamy are two very different things: polyam is having more than one partner in an ethically non-monogamous set up” (Mumsnet, December 2018).

The table covers the US only. We found nothing comparable in the UK or Sweden.

Not legal advice. Checked October 6, 2026.