Lois Lowry was born in 1937 in Honolulu, Hawaii. Because her father was a career army officer, Lowry moved around as a child. She lived in several different countries including Japan. She attended Brown University, where she was a writing major, but left college before graduation to get married. Lowry's marriage did not last, but she had four children who became inspirational in her work. She finished her college degree at the University of Maine and worked as a housekeeper to earn a living. She continued to write, however, filled with ideas by the adventures of her children. In addition to working on young adult novels, Lowry also wrote textbooks and worked as a photographer specializing in children's portraits.

For her first novel, A Summer to Die, Lowry received the International Reading Association Children's Book Award in 1978. The novel tells the story of a thirteen-year-old girl's complex feelings toward her older sister, who is dying. Lowry has said that she does not like to include directly autobiographical information in her books, but it is possible that some of Lowry's experience seeped into A Summer to Die, for Lowry's own sister died of cancer.

Number the Stars is one of more than twenty young adult novels Lowry has written. Lowry is the author of the popular Anastasia series. Lowry has been awarded numerous book awards. In 1990, Number the Stars won the Newbery Medal and the National Jewish Book Award. More recently, Lowry has received praise for her novel The Giver, written in 1993. Lois Lowry's interest in the German occupation of Denmark during the Second World War was piqued by a friend's stories. Annelise Platt, to whom Number the Stars is dedicated, experienced many of the events which occur in the novel. Apparently a great and willing storyteller, Platt described the privations and trial that she and her family went through during the years of the war. She also told Lowry of the great devotion of the Danes to their king and country. As Lowry says in the Afterword to Number the Stars, Annemarie Johansen is a fictional little girl, but she grew out of the stories of Annelise Platt's own childhood.

Though events of Number the Stars are based in actual historical fact, the specific story is Lowry's own mixture of fiction, oral histories, and research. The novel takes place in Denmark in 1943, three years after the Germans invaded Denmark. King Christian X was the Danish king from 1912 to 1947. He had a cold and indifferent attitude towards the Nazis and was unwilling to recognize their public presence. The King's attitude the attitude of the Danish people toward their invaders. One of the unique aspects of the German occupation of Denmark was that the monarchy was left intact. Other concessions were also made to the Danes, largely because they provided food and transportation for Hitler's army. However, these concessions did not erase the offense of the occupation, and a resistance movement gathered force in 1942 and was mobilized in 1943. The greatest accomplishment of the Danish Resistance was the mass rescue of Danish Jews in October of 1943.

Although King Christian is the only purely historical figure in Number the Stars, Lowry based several of her characters on real people. Peter Neilsen was directly inspired by the life of a young man who was part of the Danish Resistance. Lowry explains in her Afterword that she encountered the name Kim Malthe-Brunn while reading about the Resistance leaders of Denmark. She was struck by his story and by the youthfulness of a picture that accompanied the text. Like the fictional Peter, Malthe-Brunn was very young and extraordinarily committed to his beliefs. In the Afterword of Number the Stars, Lowry includes an excerpt from a letter that Malthe-Brunn wrote to his family from a German prison on the night before he died. In the novel, Peter, who dies in the same way Malthe-Brunn died, also sends a letter from prison to the Johansens.