Margaret Koester was born in Pittsburgh, PA, the youngest of seven children of Irish immigrant parents.

She lived in Pittsburgh most of her life, part of which was spent employed in the Personnel office of Westinghouse Electric Corporation as an interviewer of women.

In 1943, Margaret wed Charles Koester, a 1st lieutenant in the Army Signal Corps of the US Armed Forces in World War II. They had five children, 3 girls and 2 boys.

In later years, they settled in Pittsburgh, PA. Margaret continues to write books. Charlie, as he was known to his loved ones, died in 1982.