William H. Armstrong was born on September 14, 1914. He was born in Lexington, Virginia and raised on a farm in Shenandoah Valley. Attending Sunday school and church played an instrumental role in his transformation from a boy into a man, just as it does in the book Sounder. Armstrong was moved by the stories of the Bible and constantly asked questions about them. He was transferred to a men's Bible class, which paved the way for later study in college. Armstrong's interest in writing books for younger people evolved when he started teaching teenagers and when he realized that—particularly when involving the Bible—the questions of young and old people were virtually the same. This is the reason that despite the fact that Armstrong's work is considered predominantly within the genre of young adult novels, his messages and simple writing style appeal to various people from assorted age groups. Armstrong's philosophy is that a young person's will to rise and improve him or herself must be fostered in order to sustain an interest in learning and, particularly, in reading.

Armstrong attributes the beauty in his homeland to God and believes in a spiritual relationship with nature. In addition to writing, Armstrong also spent time as a farmer, carpenter, and stonemason, and he built his own home. Making something tangible that will last for a long time exemplifies his connection to God, and, this idea applies to physical structures as well as books.

The circumstances in Sounder are drawn largely from Armstrong's own life. His wife died when their three children were very young, and the children had to grow up suddenly, taking on additional responsibilities. Many of the themes that resonate through the text of Sounder were ones that applied to his personal situation. Like the children in the book, his children had to work and spend more time than usual alone.

Armstrong spent fifty-two years teaching ancient history—a profession that brought many of his loves and beliefs together. He wrote his first book—a study guide published in 1956—at the behest of the school's headmaster. Armstrong then published a number of self-help books. It was not until 1969 that he published Sounder, his most acclaimed book. The book Sour Land, published in 1971, is a sequel to Sounder, tracing the grown son's life. This book was not received with the same praise as Sounder, which had won the prestigious Newbery Award. A third book in the same series, The MacLeod Place, was published one year later. Armstrong then published a number of books about Bible characters, retelling Bible stories.