Mr. Zwerdling was born in Brooklyn. His father was in the wholesale produce business. He was a child actor with the Players Guild of Manhattan. After serving in the U.S. Air Force Special Services in World War II, 1942-45, during which time he produced and directed 95 shows for servicemen, he was producer-director for the American Players in Zurich, Switzerland, and assistant to the director of the Zurich State Theatre (1946-47). He was also director of the Kansas City Resident Theatre (1947-48).

Between 1948-60, Mr. Zwerdling worked for eight theatrical periodicals, and his writing appeared in many newspapers. He also wrote plays. He was a writer and editor at Show Business before he started Back Stage.

Back Stage — which was sold to Billboard Publications in 1986 — has a current circulation of 32,000, a spinoff publication (Back Stage West, based in Los Angeles) and a website.

Mr. Zwerdling, who retired to a farm, is survived by daughters Sherry Zwerdling of Key West, FL, and Jan Heyes of Topanga Canyon, CA; son Gary Zwerdling of Rosendale; and a grandson. His wife since 1946, Shirley M. Zwerdling, died in 2008.