Mr. Wallach was born in 1927 in The Bronx. He joined the Navy in 1946. After getting married and moving to Connecticut in 1953, he took a job at the New Haven Register as a reporter. Later in the decade, he moved on to Newsday. He stayed with the paper for three decades.
As Newsday's theatre critic and entertainment editor, he wrote reviews and feature stories about theatre artists. He also reported on the theatre scenes in cities outside the New York area. His final article was published in 2000.
From 1986 to 1988, he was president of the New York Drama Critics' Circle. He also played a role in the annual awarding of the George Oppenheimer Playwriting Award, named for his predecessor at the Newsday reviewing post.