In the course of every musical’s life, there are few moments more magical than the sitzprobe. A German term of musical theater and opera meaning “seated rehearsal,” the sitzprobe is the first time the orchestra and actors unite to integrate the complete score. It’s a special moment for the cast to absorb the music they’ve been experiencing, orchestra-less, in the rehearsal room for weeks. And with a 18-piece orchestra giving life to Leonard Bernstein’s majestic score, it’s also a celebratory moment in the process of creating an equally celebratory musical.

The score of Wonderful Town exudes a sense of joy and discovery and, as observed at this particular rehearsal late last week, the cast is similarly elated to be there. Donning casual rehearsal clothes, the 26-member company of actors, singers and dancers assembles on the stage—some wearing caps from earlier wig fittings, others huddling under blankets to keep their voices and limbs warm. It’s a casual setting, but the excitement in the room is palpable; the cast can’t help but tap their toes along to the music and rehearse bits of choreography from their seats.

While the sitzprobe is a joyous moment, it’s also a serious one. Music director Doug Peck commands the rehearsal with extreme focus and attention to detail, hitting each note with precision and making clear his intention to honor Bernstein’s score to the letter. Guiding cast and orchestra through the score and fielding questions as they arise on this first pass, he hones in on moments where tempo (speed) or dynamics (volume) need adjustment. When the orchestra launches into “Swing!,” one of the most musically complex numbers in Wonderful Town, Peck describes the need to find carefully choreographed chaos. It’s a thrilling moment to observe, and a reminder that this is challenging work—despite how, in performance, Bernstein’s music seems to float effortlessly from actors’ voices and musicians’ instruments. Peck has the orchestra and company run through the number several times before declaring victory.

In addition to the 20 songs and reprises of Wonderful Town, the sitzprobe also includes the overture (the opening music), the entr’acte (the piece of music between the show’s two acts, following intermission) and all incidental music (bits of music between scenes). And while normally the overture comes at the top of the show, Peck chooses to conclude the sitzprobe with it. He invites the actors to sit in the audience, so that they truly have an opportunity to sit back, relax and enjoy the music. Grinning with excitement, the cast takes a seat in the house as the overture begins to play—everyone falling “A Little Bit in Love” with Bernstein’s incredible composition.