Bigamy and polygamy are terms used to describe marriage arrangements involving more than two spouses, but they do not mean the same thing. While both involve a person having multiple marital relationships, the circumstances and legal implications can differ significantly.
Bigamy generally refers to marrying another person while an existing legal marriage remains in place. Polygamy describes a marriage arrangement in which someone has more than one spouse at the same time.
The distinction matters because bigamy is generally treated as a criminal offence in jurisdictions such as the United States, while polygamy has different cultural, religious and legal meanings across the world.
Understanding these terms also requires looking at related arrangements, including polygyny, polyandry, group marriage and consensual non-monogamous relationships.
What Is Bigamy?
Bigamy occurs when someone enters into a second marriage while still legally married to another person.
For example, someone who marries a new partner without legally ending their first marriage may be committing bigamy.
The circumstances can vary. In some cases, the person entering the second marriage deliberately conceals the existing marriage from the new spouse. In others, both partners may know about the situation and agree to it.
Bigamy can also happen unintentionally. Someone may believe a divorce has been finalised when the legal process is still incomplete.
In the United States, bigamy is illegal, although the specific criminal penalties and legal consequences vary by state.
The important distinction is that bigamy involves entering into a marriage while another legally recognised marriage remains in force.
What Is Polygamy?
Polygamy is a marriage arrangement in which one person has more than one spouse at the same time.
Unlike bigamy, which commonly involves an additional marriage entered into while an earlier legal marriage remains valid, polygamy is a broader description of a marriage structure involving multiple spouses.
Polygamous arrangements can take different forms depending on the gender of the people involved and the structure of the union.
The three main classifications discussed in the source material are polygyny, polyandry and group marriage.
The Different Types of Polygamy
1. Polygyny
A man married to multiple women
Polygyny refers to a marriage arrangement in which one man has multiple wives simultaneously.
It is one of the most widely documented forms of polygamy and has existed in different societies throughout history.
The source material identifies examples from historical Chinese, Hebrew, Hindu and Arab cultures, as well as communities in parts of Africa and South America.
Several factors may influence the practice, including cultural traditions, religious beliefs, economic circumstances and family structures.
Some communities associate polygyny with a man’s ability to provide financially for multiple households or spouses. Religious interpretations can also influence whether the arrangement is accepted within a particular community.
The source material identifies two forms of polygyny:
- Sororal polygyny: A man marries two or more women who are sisters.
- Non-sororal polygyny: A man marries multiple women who are not related to one another.
The prevalence and acceptance of polygyny vary considerably between countries and communities.
2. Polyandry
A woman married to multiple men
Polyandry is a marriage arrangement in which one woman has more than one husband at the same time.
It is less commonly documented than polygyny and is associated with particular communities and cultural traditions.
The source material discusses two forms:
- Fraternal polyandry: A woman is married to two or more brothers.
- Non-fraternal polyandry: A woman is married to multiple men who are not related to one another.
The source also references the Mosuo people of China, describing their matrilineal family structure and relationship traditions. However, the exact description of their relationship system should be checked against specialist anthropological sources before publication. Their practices should not automatically be classified as conventional polyandrous marriage.
3. Group Marriage
Group marriage involves multiple men and women forming a shared marriage-like arrangement.
Rather than one person having several spouses individually, the relationship structure involves several participants who consider themselves part of the same marital union.
This arrangement is distinct from a conventional polygynous or polyandrous marriage because it can involve multiple husbands and wives within one group.
Group marriage is uncommon, and its legal recognition varies depending on the jurisdiction.
Bigamy vs Polygamy: The Major Differences
Although bigamy and polygamy both involve multiple marital relationships, several distinctions help explain how they differ.
| Feature | Bigamy | Polygamy |
|---|---|---|
| Meaning | Entering another marriage while already legally married | Having multiple spouses simultaneously |
| Marriage structure | Involves a second marriage while an earlier legal marriage remains valid | Can involve a recognised arrangement with multiple spouses |
| Awareness | A spouse may be unaware of the existing marriage, although all parties may know | Spouses are generally aware of the shared marriage arrangement |
| Legal position | Criminalised in jurisdictions such as the United States | Legal status varies by country and jurisdiction |
| Relationship structure | May involve separate marriages and households | May involve spouses sharing a household or maintaining separate homes |
| Cultural context | Often associated with an unauthorised additional marriage | May be connected to cultural or religious traditions |
One important qualification is that these are general distinctions. Legal definitions and recognition differ between countries, and not every polygamous relationship is legally recognised as a marriage.
Is Bigamy the Same as Polygamy?
No. Although the terms are sometimes used interchangeably, they describe different circumstances.
Bigamy specifically concerns entering into another marriage while an existing legal marriage has not ended.
Polygamy is a broader marriage arrangement involving multiple spouses at the same time.
For example, someone who secretly marries a second person while remaining legally married to their first spouse may commit bigamy.
By contrast, a person in a community where polygamous marriage is legally recognised may have multiple spouses under that country’s marriage laws.
The legal status of either arrangement depends on the laws governing the marriage.
Other Relationship Arrangements That Are Often Confused With Polygamy
Not every relationship involving multiple partners is a polygamous marriage. Some arrangements involve romantic or sexual relationships without creating multiple legal marriages.
Open Marriage
An open marriage is an arrangement in which married partners agree that they may have sexual relationships with people outside their marriage.
The central feature is mutual agreement and transparency.
Unlike polygamy, an open marriage does not necessarily involve additional spouses. Partners may remain legally married to each other while maintaining relationships outside the marriage.
Polyamorous Relationships
Polyamory refers to having or being open to multiple romantic relationships with the knowledge and consent of everyone involved.
People in polyamorous relationships may form different types of connections, including triads, quads and other relationship structures.
Some arrangements involve established primary partnerships, while others do not prioritise one relationship over another.
Polyamory is not automatically the same as polygamy. People can have multiple romantic partners without being married to them.
Ethical Non-Monogamy
Ethical non-monogamy is a broad term for relationship arrangements in which partners mutually agree that romantic or sexual connections outside their primary relationship are permitted.
It can include open relationships, swinging and polyamory.
Honesty, communication and consent are central to these arrangements.
Unlike bigamy, ethical non-monogamy does not necessarily involve entering into another legal marriage.
Legal and Cultural Perspectives on Multiple Marriages
The legal treatment of bigamy and polygamy differs across the world.
In the United States, bigamy is illegal, and marriage laws generally do not recognise multiple simultaneous legal spouses.
Other countries have different approaches to polygamous marriage. Some jurisdictions permit certain forms of polygyny under specific legal or religious conditions, while others prohibit multiple marriages.
Even where polygamy is permitted, the law may impose requirements concerning registration, financial responsibilities and the rights of spouses.
Cultural acceptance should also be distinguished from legal recognition. A marriage arrangement may be practised within a community without being recognised by the country’s civil marriage laws.
Anyone considering marriage across jurisdictions should understand the applicable legal requirements rather than relying on cultural customs or religious ceremonies alone.
The Bottom Line
Bigamy and polygamy both involve multiple marital relationships, but the terms describe different arrangements.
Bigamy generally means entering into another marriage while an existing legal marriage remains in place. Polygamy describes a marriage structure involving more than one spouse at the same time.
Polygyny, polyandry and group marriage are different forms of polygamous arrangements, while open marriages and polyamorous relationships are broader relationship structures that do not necessarily involve multiple legal spouses.
Understanding these distinctions helps clarify the difference between marriage law, cultural traditions and consensual relationship choices.