He arrived holding a textbook called “Basic Medical Endocrinology,” which he had been studying on the subway. Once the shortest boy in the chorus, with big, dark eyes and thick black bangs, he was now a muscular 5-foot-8, and his hair was shorn in a crew cut.

Years ago, his mother had gone to Brooklyn Tech, one of the city’s test-based high schools. Jamie excelled at Celia Cruz Bronx High School of Music and was accepted at New York University, where he is a biology major studying for an M.D. and a Ph.D. He studied piano at Juilliard during high school, affirming Ms. Grussner’s belief that he was probably the most talented member of the chorus. Even now, he said, he retreats to the practice rooms to play when he is under stress.

“I got three hours of sleep last night,” Mr. Flores said at the reunion, guzzling from a mug of coffee, then joining Mr. Maldonado in a rum and coke. The transition from the Bronx to Washington Square Park had its rough spots.

“N.Y.U. compared to my high school academics was like, I was like the dumb Latino trying to struggle,” Mr. Flores said, with ruefulness and bravado. “I went from, like, almost passing Math B to, like, college calculus.” Sophomore year was brutal, and he thought about giving up. “After that, it all got better; something clicked,” he said. “I drank some smart juice or something.”

Erica Davies, still tall and swanlike, glided in three hours late, admitting that she had been a little nervous about coming, but adding: “As soon as I looked in the window, I was like, Yes! I know everybody.” The daughter of a preschool teacher, she went to the Ethical Culture Fieldston School on a scholarship. She is now studying economics at Lehman College, in the Bronx. The pizzeria reminded her of private school. “I used to wish I lived in this neighborhood,” she said wistfully. “Most of my friends in high school lived between 72nd and 110th, on Riverside Drive and Central Park West.”

Between pizza and tiramisù, the group went outside to take pictures. One of the girls worried that Ms. Grussner, in ballet flats and leggings, looked frail. “I used to wear heels a lot, but my legs are too weak; they can’t really make it anymore,” Ms. Grussner said, her only allusion to the diagnosis of muscular dystrophy that contributed to her decision to move back home.