Harry Mazer was born on May 31, 1925, in New York City. His parents, Sam and Rose Lazernick Mazer, were both dressmakers in a factory. His family of cousins, aunts, and uncles were Polish and Russian Jewish immigrants. During Mazer's childhood, reading was his greatest pleasure. However, since there were few books in his parents' home, mostly sets of classics that were obtained through various newspaper promotions, the library became the place that could satisfy his hunger for reading. As a young boy, he had a plan to read all the books in the library, starting with the letter A. During high school, he made some attempts at writing, but was not satisfied with the results. All he could do, he said, was compare what he had written with the classics he had read, and the contrast made his efforts seem hopeless. Still, he dreamed of writing.
After graduating from Union College in 1948, Mazer married Norma Fox, who also loved books and was a writer. During the early years of their marriage, though, life provided few opportunities for Mazer to write. Kept busy with the business of being a husband, father, and provider, he worked at various times as a longshoreman, railroad worker, teacher, welder, and iron worker. However, he became more and more dissatisfied with this work and yearned to devote his attention to writing. Mazer credits his wife, Norma, with encouraging him to pursue his writing career. While trying to support his family by working at various jobs, he and his wife would rise at 3:30 in the morning, so that they both might write for three hours before Mazer had to leave for work. Not until he was in his middle thirties did Mazer feel confident enough about his writing to forego the security of the factory paycheck and become a full-time writer. Harry and Norma, who has also become an acclaimed young adult novelist, have collaborated on three novels: The Solid Gold Kid (1977) and more recently, Heartbreak (1989) and Bright Days, Stupid Nights (1992). Although most of their literary work has been done separately, they do discuss and consult with each other about what they are writing.
Critics have pointed out that Harry Mazer writes about young people who are caught in moral dilemmas, which they, themselves, have often created. In extricating themselves from these crises, they discover who they are. Thus, many of his protagonists find themselves in trouble, run away from the problem confronting them, and yet in the end return to face the problem with new strength and insight. Mazer's novels for young adults have received numerous awards, including Kirkus Choice list, 1974, for The Dollar Man and Children's Choice list (International Reading Association), 1977, for The Solid Gold Kid. His work has been selected for the American Library Association's Best Books for Young Adults list: in 1977, for The Solid Gold Kid; in 1978, for The War on Villa Street; in 1979, for The Last Mission; in 1981, for I Love You, Stupid!; in 1986, for When the Phone Rang; and in 1987, for The Girl of His Dreams. He has received a Dorothy Canfield Fisher Children's Book Award nomination, 1979, for The War on Villa Street. His book The Last Mission appeared in the New York Times Best Books of the Year list, 1979, the New York Public Library Books for the Teen Ager list, 1980, and the ALA Best of the Best Books list, 1970-1983. Snowbound was placed in the Booklist Contemporary Classics list, 1984, and received the German Preis der Lesseratten. He received the Arizona Young Readers Award nomination, 1985, for The Island Keeper. The book When the Phone Rang was included in the Iowa Teen Award Master list. Some of Mazer's novels have been translated into German, French, Danish, and Finnish.