Stafford was born in Hutchinson, Kansas, the oldest of three children in a highly literate family. During the Depression, his family moved from town to town in an effort to find work for his father. Stafford helped contribute to family income by delivering newspapers, working in sugar beet fields, raising vegetables, and working as an electrician's apprentice. During this time he had a near death experience in a local swimming hole.
He graduated from high school in the town of Liberal, Kansas in 1933. After attending junior college, he received a B.A. from the University of Kansas in 1937. He was drafted into the United States armed forces in 1941, while pursuing his master's degree at the University of Kansas, but declared himself a conscientious objector. As a registered pacifist, he performed alternative service from 1942 to 1946 in the Civilian Public Service camps. The work consisted of forestry and soil conservation work in Arkansas, California, and Illinois for $2.50 per month. While working in California in 1944, he met and married Dorothy Hope Frantz with whom he later had four children (Bret, who died in 1988; Kim, writer; Kit, artist; Barbara, artist). He received his M.A. from the University of Kansas in 1947. His master's thesis, the prose memoir Down In My Heart, was published in 1948 and described his experience in the forest service camps. That same year he moved to Oregon to teach at Lewis & Clark College. In 1954, he received a Ph.D. from the University of Iowa. Stafford taught for one academic year (1955–1956) in the English department at Manchester College in Indiana, a college affiliated with the Church of the Brethren where he had received training during his time in Civilian Public Service. The following year (1956–57), he taught at San Jose State in California, and the next year returned to the faculty of Lewis & Clark.
One striking feature of his career is its late start. Stafford was 46 years old when his first major collection of poetry was published, Traveling Through the Dark, which won the 1963 National Book Award for Poetry. The title poem is one of his best known works. It describes encountering a recently killed doe on a mountain road. Before pushing the doe into a canyon, the narrator discovers that she was pregnant and the fawn inside is still alive.
Stafford had a quiet daily ritual of writing and his writing focuses on the ordinary. His gentle quotidian style has been compared to Robert Frost. Paul Merchant writes, "His poems are accessible, sometimes deceptively so, with a conversational manner that is close to everyday speech. Among predecessors whom he most admired are William Wordsworth, Thomas Hardy, Walt Whitman, and Emily Dickinson." His poems are typically short, focusing on the earthy, accessible details appropriate to a specific locality. Stafford said this in a 1971 interview:
I keep following this sort of hidden river of my life, you know, whatever the topic or impulse which comes, I follow it along trustingly. And I don't have any sense of its coming to a kind of crescendo, or of its petering out either. It is just going steadily along.
Stafford was a close friend and collaborator with poet Robert Bly. Despite his late start, he was a frequent contributor to magazines and anthologies and eventually published fifty-seven volumes of poetry. James Dickey called Stafford one of those poets "who pour out rivers of ink, all on good poems." He kept a daily journal for 50 years, and composed nearly 22,000 poems, of which roughly 3,000 were published.
In 1970, he was named Consultant in Poetry to the Library of Congress, a position that is now known as Poet Laureate. In 1975, he was named Poet Laureate of Oregon; his tenure in the position lasted until 1990. In 1980, he retired from Lewis & Clark College but continued to travel extensively and give public readings of his poetry. In 1992, he won the Western States Book Award for lifetime achievement in poetry.
Stafford died of a heart attack in Lake Oswego, Oregon on August 28, 1993, having written a poem that morning containing the lines, "'You don't have to / prove anything,' my mother said. 'Just be ready / for what God sends.'" In 2008, the Stafford family gave William Stafford's papers, including the 20,000 pages of his daily writing, to the Special Collections Department at Lewis & Clark College.
Kim Stafford, who serves as literary executor for the Estate of William Stafford, has written a memoir Early Morning: Remembering My Father, William Stafford (Graywolf Press).