Even though “Company” is all about marriage, at the center of Stephen Sondheim’s musical comedy is Robert, a single guy celebrating his 35th birthday.

What better way for Robert to explore the possibilities of marriage than by observing the married couples who are throwing his surprise party? There are five of them, all with a different take on marriage. None are perfect, but Robert will learn that all are interesting when Theatre Baton Rouge opens “Company” on Friday, March 6.

“And we learn that marriage is as complicated in this day and age as it’s ever been,” says Jenny Ballard, the theater’s managing artistic director. “This story is told through comedy, but people will be able to identify with it — people who are married and people who aren’t.”

Ballard directs this production of 14 cast members who will perform to two on-stage pianos. Terry Bowman is the musical director, and Mary Bayles is the choreographer.

“Company,” which made its Broadway debut in 1970, is based on a book by George Furth with Sondheim writing music and lyrics. It was one of the first musicals to address adult themes and relationships.

“Broadway theater has been for many years supported by upper-middle-class people with upper-middle-class problems,” Sondheim said in the 2004 PBS documentary, “Broadway: The American Musical.” “These people really want to escape that world when they go to the theater, and then here we are with ‘Company’ talking about how we’re going to bring it right back in their faces.”

The hit show earned 14 Tony nominations and six wins. Sondheim and Furst reprised “Company” in the 1990s with updated dialogue, but the story remained the same.

“The story is really a series of vignettes,” Ballard says. “It’s a party, so everyone is always on stage, and the story flows from one couple to the next.”

And Robert thinks about his own situations in between, imaging how life would be with each of three past girlfriends.

“This part is happening in Bobby’s head, but we get to see this play out,” Ballard says. “We’re seeing what he wants out of a relationship as he journeys through these vignettes, and we begin to understand that you have to know who you are as a person before you can understand who the other is.”

As he steps into the role of Bobby, Jason Dowies can’t help identifying with his character. He, too, is a single guy in his 30s.

“Unlike Bobby, I’ve been married before, but now that I’m in my 30s, people are wondering when I’m going to get married again,” he says, laughing. “It makes it personal for me.”

Fellow cast member Jennifer Johnson plays Joanne, a woman who realizes in middle age that she may have wasted her life.

“She fears that she hasn’t accomplished anything,” Johnson says. “She’s spent all of her time indulging herself and playing, but what has she done? She isn’t aging gracefully.”

Many Sondheim fans will recognize Joanne as the character who sings his show-stopping hit, “Ladies Who Lunch.”

Joanne is married to Larry, played by Terry Byars. The couple seems happy when they’re around others.

“But to Bobby, they seem to be playing some kind of game,” Johnson says.

“Bobby has his fears,” Dowies adds. “He talks about how there would always be another person around if he got married, and he could never get away from that. And when he thinks of his three girlfriends, it’s as if he’s pulling them together into one and coming up with a version of what he wants life to be.”

Still, Bobby has yet to commit fully to a steady relationship.

“It’s like he’s a special toy waiting on a shelf, waiting for someone to take him off,” Dowies says.

Bobby may find some answers through interaction with his friends.

Audience members may learn a few things, too.

“It’s a musical comedy, but I hope that people will watch this and examine their own relationships,” Ballard says.