In the course of her career Lortel produced or co-produced nearly 500 plays, five of which were nominated for Tony Awards: As Is by William M. Hoffman, Angels Fall by Lanford Wilson, Blood Knot by Athol Fugard, Mbongeni Ngema's Sarafina!, and A Walk in the Woods by Lee Blessing.

She also produced Marc Blitzstein's adaptation of Bertolt Brecht and Kurt Weill's Threepenny Opera, a production which ran for seven years and according to The New York Times "caused such a sensation that it...put Off-Broadway on the map.

[6] According to Lortel's wishes, the theater's mission was to present works of an unusual and experimental nature, existing as a sanctuary from commercial pressures, a place where writers could take a chance with their plays and where actors could stretch their talents.

[1] Under Lortel's guidance, the White Barn premiered plays (many of which enjoyed successful transfers to commercial theatres) including: George C. Wolfe and Lawrence Bearson's Ivory Tower with Eva Marie Saint (1947); Seán O'Casey's Red Roses for Me (1948); Eugène Ionesco's The Chairs (1957); Archibald MacLeish's This Music Crept by Me Upon the Waters (1959); Edward Albee's Fam and Yam (1960); Samuel Beckett's Embers (1960); Murray Schisgal's The Typists (1961); Adrienne Kennedy's The Owl Answers (1965); Norman Rosten's Come Slowly Eden (1966); Paul Zindel's The Effect of Gamma Rays on Man-in-the-Moon Marigolds (1966); Terrence McNally's Next (1967); Ahmed Yacoubi's The Night Before Thinking (1974); Barbara Wersba's The Dream Watcher starring Eva Le Gallienne (1975); June Havoc's Nuts for the Underman (1977); David Allen's Cheapside starring Cherry Jones (which Lortel later co-produced at the Half Moon Theatre in London); and Jerome Kilty's Margaret Sanger: Unfinished Business, starring Eileen Heckart (1989).

[5] Among the successful transfers to Off-Broadway from the White Barn Theatre were: Fatima Dike's Glasshouse, Casey Kurtti's Catholic School Girls, Diane Kagan's Marvelous Grey, and Hugh Whitemore's The Best of Friends.

Hotchner's Welcome to the Club (which premiered at the White Barn as Let 'Em Rot) and Lanford Wilson's Redwood Curtain, later on television as a Hallmark Hall of Fame 1995 production.

As Threepenny Opera continued and eventually concluded its run, Lortel produced many other plays, including Jean Genet's The Balcony in 1960, which won the Village Voice's Obie Award for best foreign play; Athol Fugard's The Blood Knot starring James Earl Jones;[8] Christopher Fry's A Sleep of Prisoners; Seán O'Casey's I Knock at the Door, Pictures in the Hallway, and Cock-A-Doodle-Dandy; Charles Morgan's The River Line with Sada Thompson, Beatrice Straight, and Peter Cookson; and Tom Cole's Medal of Honor Rag.

During the 1983/84 season, Lortel co-produced Michael Cristofer's The Lady and the Clarinet starring Stockard Channing, followed by Woza Albert!, which received an Obie Award.

In 1985, she produced Win Wells' Gertrude Stein and a Companion starring Jan Miner and Marian Seldes in the roles they'd originated at the White Barn.

The theater housed her production of Jane Anderson's The Baby Dance, as well as Terrence McNally's Lips Together, Teeth Apart, and Nicholas Wright's Mrs. Klein (produced by Lortel) and Donald Margulies' Collected Stories, both starring Uta Hagen.

Two productions that began in the Matinee Series went on to the Festival of Two Worlds in Spoleto, Italy: Tennessee Williams' I Rise In Flame Cried The Phoenix and Meade Roberts' Maidens and Mistresses at Home in the Zoo, the latter of which also played Off-Broadway.

Shaw's Candida; a dramatic recital by Sybil Thorndike and Lewis Casson (married in real life); Walter Abel, Richard Burton and Cathleen Nesbitt in An Afternoon of Poetry; and Orson Bean in A Round with Ring.