Her books are typically recommended to age groups 8-16 years, but they include elements even for adult readers. Her best known book is I Am David (1963) (translated into the English novel I Am David; adapted for a 2003 film; also published as North to Freedom), which tells the story of a 12-year old boy who escapes from a concentration camp and travels through Europe. It won the ALA Notable Book award in 1965, the 1963 Best Scandinavian Children's Book award and the Boys Club of America Junior Book Award Gold Medal.
Another well known book by Holm is Stacy (1966), which tells the story of a teenage boy who travels in time to ancient Greece and medieval England.
Holm was born in Oksbøl. She married J.C Holm in 1949.