What is the difference between polyamory and polygamy?

Polygamy is about marriage. It describes one person being married to more than one spouse at the same time — polygyny is one husband with several wives, polyandry is one wife with several husbands. Because it is a marriage structure, polygamy is a legal question, and in the United States it has no legal standing: marriage is licensed between two people, and a second marriage while a first still exists is bigamy — the later marriage is void and may be annulled (Cornell Law School, Legal Information Institute).

Polyamory is about relationships, not marriages. It means having more than one loving relationship at the same time, with the knowledge and consent of everyone involved. The shapes vary — one person with two partners who are not involved with each other, three people all involved with each other, or a wider connected network — and none of them requires a wedding, a shared address or a shared bank account.

The two get confused because both involve more than one partner, and because headlines often use the word polygamy loosely for any arrangement with several adults in it. In practice they differ on nearly every axis that matters. Consent and open knowledge are definitional in polyamory; polygamy names a marriage form and says nothing about how the arrangement was entered into. Polyamory is generally gender-symmetric in a way that polygyny — one man, several wives — is not. And polyamory is a private agreement, while polygamy is a claim on marriage law.

The legal positions differ too, and the difference cuts both ways. Bigamy is a marriage in which one of the parties is already legally married: the later marriage is void and may be annulled, while the first marriage is unaffected (Cornell Law School, Legal Information Institute). Marriage law therefore recognises one spouse at a time, however many relationships someone has. Having several consensual relationships is not itself the offence — the offence is marrying again while a first marriage exists. Polling reflects the same gap: in a February 2023 YouGov survey of US adults, 68% opposed legalising polygamy, and polyamory drew less disapproval than polygamy did. None of this is legal advice; a family lawyer in your state is the right source for your situation.

Where does the lifestyle fit? Swinging is typically couple-anchored and recreational, polyamory usually centres on ongoing romantic relationships, and polygamy is a marriage structure. They can overlap, but most people in the lifestyle are neither polygamous nor polyamorous. The lifestyle glossary and the ethical non-monogamy guide set out how the labels relate.