Mr. Cook founded Theatre Genesis in 1964. Its home base was St. Mark's Church-in-the Bowery in the heart of the then-sketchy East Village. As artistic director, he produced the early work of Lanford Wilson, Leonard Melfi, Charles L. Mee, H.M. Koutoukas, and, most famously, Sam Shepard, who has since spoken of Theatre Genesis as his artistic birthplace.

Together with Caffe Cino, La MaMa E.T.C. and Judson Poets Theatre, the company is considered one of the four seminal stages from which the Off Off-Broadway movement was launched (though, over time, perhaps due to its short lifespan and insular artistic approach, it has become the least remembered). Together, the quartet of companies reclaimed the scrappy sense of invention and creativity that they felt had been lost as the Off-Broadway companies created in the 1950s had been co-opted by commercial concerns.

As the story goes, Mr. Cook, who had been recovering from a mental breakdown and a stay in the hospital, stumbled into St. Mark's one Sunday. He became enthralled with one of the sermons delivered by Michael Allen, the community-minded rector of church (and a former editor at Look magazine). Soon, he was a regularly attendee and had befriended Allen. In 1963, he asked the churchman if he could form a theatre company that would perform in the church. Allen agreed.

Mr. Cook decided Theatre Genesis would be devoted to nurturing young playwrights and produce plays that spoke directly to the experience of the downtrodden citizens in the immediately area. Of the outside theatre community, he once said, "We couldn't care less about Broadway. We are aware that it exists somewhere uptown, no more." He invited his young friends—including Shepard and Melfi—to submit scripts.

An early production was the double bill of Shepard's Beckett-influenced one-acts Cowboys and The Rock Garden. Shepard was 20 at the time; the two men had met at the Village Gate, where Shepard was a busboy and Cook was headwaiter. Mainstream critics didn't care for the work, but The Village Voice singled Shepard out for praise as an emerging voice. "Cook and his playwrights are hot for adventure," Michael Smith wrote in The Voice in 1966. Their plays "reflect reality at a more abstract level: contemporary, urban rhythms of speech, deflected and diffuse communication between characters, disquieting patterns of self-awareness."

The production atmosphere was catch-as-catch-can. "We had no money," recalled Shepard. "I can remember getting props off the street. We'd take Yuban coffee cans, punch a hole in them, and use them for lights. We did it all from scratch, which was pretty incredible."

Shows were presented in the second-floor meeting room of the parish hall, which Mr. Cook converted into a tiny black box theatre. Notable productions included Koutoukas' Medea, which set the Greek tragedy in a laundromat (the show was simultaneously performed, in a different production, at Caffe Cino, unbeknownst to Cook); The Hawk, an examination of drug addiction by Murray Mednick; and Birdbath by Melfi, who would become the theatre's most-produced playwright. Birdbath became Melfi's greatest success, receiving productions elsewhere in New York.

Mr. Cook—described at the time as "a tall, black-haired, ascetic-looking man with an inward-turned expression in his black eyes and a general air of concerning himself only with essentials"—took his title of artistic director seriously. He selected every play presented, and directed most of the productions. Still, he did not interfere with the work of the writers and players, but helped them find their way themselves. Mr. Cook used the same playwrights and actors (including Barbara Eda-Young, who was a regular) again and again, creating a family atmosphere of sorts.

Genesis productions were often characterized by a certain free-wheeling, rangy machismo which stood in stark contrast to the frequently campy atmosphere at Caffe Cino. Plays by women were almost never produced. One playwright described the prevailing vibe as "a bunch of guys, and their babes, and their drugs."

Later in the '60s, as the Off Off-Broadway scene grew, fund-raising became a troublesome issue. Mr. Cook, predisposed toward rejecting any kind of corporate influence, found himself forced to solicit moneys from foundations. He left Theatre Genesis in 1969, leaving the group in the hands of two associates.

Ralph Cook was born in California in 1928. He enlisted in the Navy at 17 and spent his service in World War II as an officer’s driver in Hawaii. He was for a time a bit-part player in Hollywood films. Following his years at Theatre Genesis, he moved to California and pursued a wide variety of professions, including fisherman.

Mr. Cook, who was married three times, is survived by his third wife, the former Patricia Larsen, and two sons, Randall and Paul.