Proposition 31

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{{about|a novel|the question on the ballot in California in 2012|California state elections, November 2012#Proposition 31}}

{{Use mdy dates|date=March 2025}}

Proposition 31 is a 1968 novel written by Robert Rimmer that tells the story of two middle-class, suburban California couples who adopt a relationship structure of polyfidelity to deal with their multiple infidelities, as a rationalistic alternative to divorce.{{Cite web |title=Proposition 31 by Robert H Rimmer |url=https://www.fantasticfiction.com/r/robert-h-rimmer/proposition-31.htm |access-date=2022-05-08 |website=www.fantasticfiction.com}}{{Cite web |last=Rimmer |first=Robert [Henry] |date=1968 |title=Proposition 31 |url=https://openpublishing.psu.edu/utopia/content/proposition-31 |access-date=2022-05-08 |website=openpublishing.psu.edu}} The novel is presented as a case study by a psychologist supporting a fictional "Proposition 31" that would amend the California Constitution to recognize non-monogamous relationships.{{Cite web |title=ROBERT H. RIMMER, 84 |url=https://www.chicagotribune.com/news/ct-xpm-2001-08-13-0108130108-story.html |access-date=2022-05-08 |website=Chicago Tribune |language=en}} In the book, the solution to the couples' problems with adultery and the impregnation of one couple's wife by the other couple's husband is to commit to a group marriage to raise their five children in a home compound in which the husbands rotate among the wives. The book is a plea to pass this proposed proposition to offer a sane alternative to divorce.