Everyone knows that the gay rights movement began with the 1969 Stonewall Riots, right? Wrong! 1950 saw the founding of The Mattachine Society, one of the earliest homophile activist organizations in the United States, and the subject of a fascinating new historical drama based on true-life characters and events.

THE TEMPERAMENTALS (named after an early 1950s code word for “homosexual”) illuminates a relatively unfamiliar chapter in the history of homosexual rights. Lovers Harry Hay (Thomas Jay Ryan) and Viennese fashion designer Rudi Gernreich (Michael Urie) lay the groundwork for The Mattachine Society, a politically-based organization advocating the homosexual as a repressed minority.

Inspired by the work of Karl Marx, Hays scribes a manifesto and attempts to enlist like-minded men to his cause. In Los Angeles in the early 1950s, this proves difficult: bias exists even within the Hollywood and fashion communities – Gernreich himself must decide between his career and this crusade. But when the police wrongly entrap a fellow temperamental, who admits his homosexuality but adamantly denies any sexual misconduct, the ensuing trial finally brings national media attention to the Mattachine Society and their plight.

THE TEMPERAMENTALS joins The Pride and Yank! as several Off-Broadway shows coincidentally explore the legacy of the gay rights movement. Originally produced last summer at a tiny studio theatre, THE TEMPERAMENTALS proved enormously popular and moved to a larger theatre, where it again extended several times.

Playwright Jon Marans’ fact-based drama re-opened recently at New World Stages in a moody, thought-provoking production directed by Jonathan Silverstein under Josh Bradford’s simple yet effective lighting and the exposed black brick and naked hanging lightbulbs of Clint Ramos’ intentionally claustrophobic set. Mr. Ramos also provides a stylish set of costumes ranging from the McCarthy era’s conservative flannel suits to the more flamboyant frocks of the Radical Faeries, a later organization founded by Harry Hays in reaction to “straight-acting” homosexuals.

Members of the Mattachine Society. Upper left: Harry Hay (role played by Thomas Jay Ryan), L to R: Konrad Stevens, Dale Jennings (role played by Sam Breslin Wright), Rudi Gernreich (role played by Michael Urie), Stan Witt, Bob Hull (role played by Matthew Schneck), Chuck Rowland in glasses (role played by Arnie Burton), Paul Bernard.

Best known from TV’s “Ugly Betty,” Urie supplements his well-worn arsenal of television tics with surprising depth in his charismatic performance as Gernreich, while Thomas Jay Ryan carries the show on his back in an alternating furious and brooding performance as Harry. The rest of cast is pretty sensational too, portraying a wide range of familiar and unfamiliar characters. Highlights include Arnie Burton as Hollywood director Vincente Minneli and Sam Breslin Wright in a haunting performance as the accused lynchpin Dale Jennings.

The battle for gay rights is far from over; debate over the military’s “Don’t Ask, Don’t Tell” policy and the battle over same-sex marriage occupy news headlines on a regular basis as the political descendents of Harry Hays and the Mattachine Society continue to fight for equality. If it were it not for these brave 1950s revolutionaries, where would today’s warriors be?

THE TEMPERAMENTALS is currently on sale through May 26. Performances are at Mondays, Thursdays, and Fridays at 8pm, and Saturdays at 2pm and 8pm, and Sundays at 3pm and 7pm. Tickets, priced $65, are available by phoning (212) 239-6200 or by visiting Telecharge.com. New World Stages is located at 340 West 50th Street.