In 1976, he came to New York with his wife to work as a contractor — sewing for designers like Michael Kors, now a judge on “Project Runway.” He moved quickly into dealing fabric wholesale, and, in the 1980s when domestic manufacturing dropped, selling retail. His wife, Janet, now 57, ran the register.

Mr. Sauma watched the other stores close while Mood stayed afloat, in part because it relied on student designers — a burgeoning group that, partly because of the show, has only grown.

Today, he has passed his duties on. “He’s kind of taking it in from the backseat,” Philip Sauma said. Philip runs the business day to day, while his brother, Eric, 29, is the creative, design-minded in-store operator. A daughter, Amy Altunis, 32, lives in London with her two young children. Recently, her nanny learned of the family business. “She screamed,” Ms. Altunis said.

“To some people it’s a big deal,” Philip Sauma said. “To us it’s work.”

“It’s not work,” Jack Sauma said. “It’s social.”

“It’s social.”