After 12 years and approximately 625 concerts, Mostly Sondheim, the venerable musical theatre open mic night at The Duplex cabaret in New York's Greenwich Village will sing its final “Side by Side” April 1.

Music director Brian Nash told Playbill.com that the night started in mid-2004 as Sondheim Fridays, hosted by Brandon Cutrell and Ray Fellman. The initial concept was of a musical theatre open mic that would highlight one composer's work exclusively per month. The second month saluted Stephen Schwartz, but then flipped back to Sondheim. By the fourth month it found its current name and concept, in simply being an all-musical theatre open mic.

The series is no relation to the Barbara Cook concert Mostly Sondheim, other than some of the subject matter.

Brandon Cutrell and Ray Fellman left in 2005 to form The After Party at the Laurie Beechman Theatre, and the evening was taken over by Nash, Marty Thomas, and Kate Pazakis. Over the years, there have been many guest hosts, but main co-hosts have been Ben Cameron and Emily McNamara.

The evening starts at 11:30 PM with the traditional sign-up, and runs until 3:45 AM. There's no cover charge, so, Nash said, “it's become a frequent must-see for theatre enthusiasts coming in from out of town on theatre weekends and for young musical theatre performers upon moving to the city. It's really become a family, and I'm incredibly proud of what we've created over the last 11 years that I've been involved.”

Among talents who have approached the mic over the years are regulars DuQuincy Cooks, Paula Galloway, Adam Feldman, Anthony Fett, David-Aidan Mackey and Rob Maitner, as well as past and present bar staff Lauren Turner, Deena Sydney and Tina Himaya.

As to why the party's over, Nash said, “Well, after 12 years, it kinda just seemed like time. I've been working so much out of town lately that I haven't been there to drive it as consistently, and many of our hosts are in the same boat. It felt better to let it go while it was still strong than maybe have it lose some following, and there really wasn't anyone waiting in the wings to take it over and reinvent it. We might bring something back at some point in a similar format, but it felt like time to close the door on this one.”

The Duplex Cabaret and Piano Bar is located at 61 Christopher St. There is a two-drink minimum but no cover.