In 1972 he became a full-time writer. He revitalized his publishing career when he met John Archambault in 1983 at UC Riverside. They went on to collaborate on more than a dozen award-winning books, including Chicka Chicka Boom Boom, and Barn Dance! and Knots on a Counting Rope, both Reading Rainbow featured selections, illustrated by Ted Rand. Their first joint work, "The Ghost-Eye Tree" won an IRA Children's Choice award and has remained in print for almost 30 years. During the last 15 years of his life, he co-wrote many books with Michael Sampson, whom he met at a reading conference in Tucson, Arizona in 1978. In 1992, Martin moved from New York to Texas to build a house beside Sampson on on the banks of the South Sulphur River. Martin named the land “Woodfrost” as a reflection of his love for Robert Frost and Frost's poetry about the woods. For the next 12 years, Sampson and Martin wrote daily, creating 25 books for children, including award winners: "I Pledge Allegiance" (illustrated by Chris Raschka) and "New York Times" best sellers "Panda Bear, Panda Bear, What Do You See?" (illustrated by Eric Carle) and "Chicka, Chicka, 1, 2, 3", (illustrated by Lois Ehlert). Their final collaboration, the "Bill Martin Jr Big Book of Poetry", was published in November 2008, four years after his death.