Sharmat was born in November 12, 1928 in Portland, Maine. After graduating from high school in 1946, she went on to Lasell Junior College in Auburndale, Massachusetts. In 1947, she transferred to Westbrook Junior College in Portland, Maine where she graduated from the following year with a degree in merchandising. When she graduated from college, Sharmat took a position with a department store, but left to take a position in the Circulation Department at the Yale University Library in New Haven, Connecticut in 1951, a position she held until 1954. At that time she transferred to join the circulation staff of the Yale Law Library, where she stayed until 1955. Sharmat's first published "work"… was a national advertising slogan for the W.T. Grant Company for their spring promotion. It was four words long. She published her first story while she was working at the library at Yale University. It was a short story for adults. Her second story was an article about Yale. It ended up becoming part of the Yale Memorabilia Collection. Her first published childrens book was Rex, 1967, and winner of the Book of the Year Citation from the Library of Congress. While the book did well, it was her third book Nate the Great, published in 1972, that really made her a writing success. In the 1960's and 1970s she wrote exclusively for children. Many of these books won awards from the Child Study Association and numerous magazines. In 1982, Sharmat broke onto the young adult writing scene with her first book, a novelization published by Dell of the CBS-TV sitcom, Square Pegs. Her first young adult novel, I Saw Him First, was published in 1989. Sharmat has written hundreds of books, mostly for children, including the "Nate the Great" series, the "Olivia Sharp, Agent for Secrets" series with her husband, Mitchell Sharmat, and "The Kids of the Bus" series with her son, Andrew. She has also written young adult novels under her own name and the name of Wendy Andrews, and the "Sorority Sisters" series.