"In our world, Mondays are Saturdays," Mamie Gummer explained last night at the Gramercy Park Hotel, where she was co-chairing the Lincoln Center Institute's Junior Spring Benefit. She recently threw her bachelorette party on a Sunday night. Welcome to the topsy-turvy schedule of a theater actress.

Whereas Gummer just closed the book on The School for Lies, Carey Mulligan has only just started piling up accolades for her star turn in Through a Glass Darkly, which runs through July 3. Normally, Mulligan explained, she spends her nights off at "the closest thing you all have to a good English pub." But her friend, actor Rightor Doyle, had persuaded her to step out for charity.

In a change of pace from movies, Mulligan is doing theater for the first time since The Seagull put her on the map in 2008. "I love kind of hanging around during the day and doing nothing, preserving all my energy for that hour and a half," she said. This being Monday, she didn't have to expend it on a bare-it-all performance that The New York Times described as "acting, at its best."

Instead, Mulligan was making cocktail party conversation in Valentino on the Gramercy's rooftop, where she was joined by Lily Rabe (who very nearly won a Tony Award on Sunday for her role in The Merchant of Venice) and Karen Elson, who performed after dinner—a warm-up, perhaps, for the divorce party she's throwing in Nashville on Friday with soon-to-be-former-husband Jack White.

Zoe Kazan and Paul Dano, meanwhile, are engaged in more traditional collaborations. They're filming a movie this summer with the Little Miss Sunshine directors, and Kazan has been soliciting her boyfriend's commentary on a play she's writing. "He gives me notes and then I go, 'You're an idiot,' " Kazan related. "And I get really mean to him for, like, six hours. And then I'm like, 'You're totally right.' " Dano shrugged. "I can't resist giving an opinion," he said. His thoughts on Kazan's play, overall? "It's very good."

— Darrell Hartman