In the summer of 2012, Tony Award-winning playwright and director James Lapine was at his home in Edgartown. Mr. Lapine loves to write while on the Vineyard but a rigid deadline from Lincoln Center’s artistic director Andre Bishop loomed, making for a pressure-filled summer. He was trying to adapt theatrical luminary Moss Hart’s memoir Act One for the stage. The task was an especially difficult one. Mr. Lapine was working with a true classic, and the adaptation had to be perfect.

Act One was published in 1959 and since then the book has remained a beloved “valentine to the theatre” that inspires young artists and reminds practitioners of what is magic about their art form. The book is often handed down from mentor to student or from friend to friend, as though a mystical initiation rite into what Moss Hart called “the THEA-tah.”

Writer/director James Lapine. — Mark Lovewell

As often as the book struck a chord with thespians, it also moved people with no connection to the theatre at all. Descriptions of Mr. Hart’s Dickensian childhood growing up in the Bronx as the offspring of immigrant cigar rollers hit home for those who lived through the Depression. His rags-to-riches biography was a Horatio Alger-like story told by someone who exemplified the American Dream. Act One can be read as a primer on how to make your way into show business, but it’s as much a tale of striving, determination, perseverance — and a little luck.

Unlike many folks in “the biz,” Mr. Lapine didn’t read Act One until he was in his 40s. He just didn’t have the kind of childhood infatuation with Manhattan and the lights of Broadway that compelled Moss Hart and so many others who live and breathe the theatre.

Mr. Lapine’s first trip to Manhattan was in the early 1960s on a family vacation from Ohio to see the original production of Bye Bye Birdie.

“I wasn’t that excited about the theatre,” Mr. Lapine said in an interview on Sunday at his office in Manhattan. “All I really wanted to do was play Keno, where if you spent $10, you could win something that probably cost 50 cents.”

Mr. Lapine did manage to inflict a paper cut on the nose of Birdie star Dick Van Dyke after vigorously shaking his programme at him while trying to procure an autograph for an eager cousin. Mr. Lapine also remembers staying at the Astor Hotel on that visit, where he could look out the window and watch the legendary Camel cigarettes billboard puff out enormous smoke rings every four seconds.

Little did he know that 30 years earlier, Moss Hart also gazed out of the windows of the Astor Hotel. On a September night now a part of theatre lore, the 26-year old Mr. Hart embraced the sight of his name in lights on a marquee, alongside that of his idol and much older writing partner, George S. Kaufman. The night Mr. Hart stood in the Astor Hotel window was his last as an unknown. His play Once in a Lifetime became a hit, and the names of Kaufman and Hart have become synonymous with “great American comedy” ever since.

When Mr. Lapine finally read Mr. Hart’s memoir, the writer in him appreciated the rich description and deeply felt emotions.

“It’s a beautifully written book,” Mr. Lapine said. “He was a great storyteller. I think that was his gift.”

Mr. Hart’s story of how he came to be paired with the legendary George S. Kaufman, and what it was like to develop a partnership with a legend, also resonated deeply with Mr. Lapine.

Santino Fontana and Andrea Martin on stage. — Joan Marcus

In 1982, composer and lyricist Stephen Sondheim (West Side Story, Gypsy, Company) attended a performance of Mr. Lapine’s play Twelve Dreams at New York’s Public Theatre. Mr. Sondheim was so impressed that he asked to meet the young artist. They began a collaboration and within two years their musical Sunday in the Park with George was an off-Broadway hit that transferred to Broadway. Mr. Lapine would win the Pulitzer Prize for the show’s libretto, a rarity for a Broadway musical. Sondheim and Lapine went on to create together revered musicals such as Into the Woods and Passion. On all of their projects, Mr. Lapine directed as well as wrote the book.

“I was very young and inexperienced when I met Steve,” Mr. Lapine said. “And I was living in a dump and going to his fancy townhouse to work with him. So when I read Act One, I said, oh, I kind of know about this situation.”

In 2011 Mr. Lapine approached Andre Bishop at Lincoln Center and proposed something often talked about but never undertaken successfully: a stage adaptation of Act One, lauded “the greatest showbiz book ever written” by critic Frank Rich. After Lincoln Center secured the rights, Mr. Lapine began reading the 444-page memoir over and over. He identified early on that the play’s structure depended on three actors to depict Moss Hart as the eager adolescent, an ambitious unknown making his way in the theatre, and the debonair bon vivant as well known for high living as for writing hit comedies and directing the original productions of My Fair Lady and Camelot.

Once he had a working draft, Mr. Lapine needed to put a cast together and hear what his play sounded like.

“If I don’t set a date to do something, I don’t do it,” he admitted. “So I thought, I’ve got the summer to write this. I’m going to have Ashley give me a week.”

The “Ashley” to whom he turned to was Ashley Melone, founder and artistic director of Vineyard Arts Project located in Edgartown, not far from Mr. Lapine’s home. The Vineyard Arts Project offers residencies for artists to develop and focus on their work without outside pressures, plus the promise of sand, surf and salt air when the work is done. Mr. Lapine had been admiring Vineyard Arts Project since the center was built.

“For years I would go by and say what is this thing? This is incredible! It’s gorgeous.”

Ms. Melone remembers well the day Mr. Lapine first stopped by to introduce himself.

“It was a surreal experience,” she said in a phone interview. “I had performed in his show Into the Woods at my high school, so I really knew who he was. It’s not every day you have someone like James Lapine knock on your door.”

When Mr. Lapine asked Ms. Melone for a week-long residency to workshop Act One, she didn’t hesitate.

During a week in July 2012, Mr. Lapine worked with a combination of Vineyard residents and visitors as well as some New York stalwarts such as Debra Monk, who had performed as Mrs. Miller in his play Mrs. Miller Does Her Thing at the Vineyard Playhouse in 2008. At the center of the cast was Emmy Award-winning actor and Vineyard seasonal resident Tony Shalhoub, whom Mr. Lapine had met socially on the Island but had never worked with before. Two readings were held at Vineyard Arts Project.

Tony Shalhoub plays three different parts in Act One. — Joan Marcus

“The first one was endless and boring,” Mr. Lapine admitted. His solution was to get a Gershwin songbook and put music into the play. Although shortly after he shed the Gershwin, the experience helped him realize that the play had to have music in it. Eventually Mr. Lapine hired Louis Rosen, a musician with extensive experience in theatrical and poetic compositions, to write music underscoring the play.

Mr. Lapine continued doing rewrites during readings in New York city, striving to capture the spirit of the book. One reading was attended by Moss Hart’s children, Chris and Cathy Hart, as well as George S. Kaufman’s daughter Anne Kaufman Schneider, whose insight into her family had helped Mr. Lapine during the adaptation process. The approval of the Harts and Mrs. Kaufman Schneider was a great sign that things were going well.

“The first reading we did for them was the most nerve wracking thing,” Mr. Lapine said. “But when it was over, they were just crying. They were so moved and so grateful.”

As Act One moved into rehearsals at Lincoln Center, Mr. Lapine shifted gears from writer to director of an enormous production of 21 actors playing more than 33 roles on a multi-tiered set. Despite wearing multiple hats on the production, he never considered the possibility of hiring someone else to shoulder the directing duties.

“I only did that once on a play and it wasn’t a very happy experience,” he said. “My wife said something to me once. ‘You don’t realize that you are working out what you do as the writer as the director.’ It’s just how I work, for better or worse. That’s how I started working and that’s what I like to do. It’s definitely harder. And with this one, it was really hard not to have a collaborator.”

When Act One opened at Lincoln Center on April 17 it was to roars of laughter, some tears of recognition and open arms from the theatre community, including the critics. On April 29, the Tony Awards committee nominated the production for five awards, including Best Play. Tony Shalhoub was nominated for Best Actor in recognition of his energetic portrayal of three leading roles, including Moss Hart in his later years and George S. Kaufman in his prime.

The opening of Act One concludes an extremely busy stretch for Mr. Lapine. He is particularly proud of the documentary Six by Sondheim that aired in December, which he created for HBO Films as a highly personal profile of his longtime collaborator. The film focuses on six of Mr. Sondheim’s most monumental songs and Mr. Lapine weaves together interviews and archival footage as well as new vocal interpretations by unconventional performers.

The Tony Awards take place on June 8. After that Mr. Lapine will get a well-deserved break from “the THEA-ter.” His plans for the summer on the Vineyard? To conquer a new challenge: he’ll be writing a TV pilot.

Act One runs at Lincoln Center’s Vivian Beaumont Theater through June 15.