Mathews' first book was a history, "Wah'kon-tah: The Osage and The White Man's Road" (1929), which was selected by the Book-of-the-Month Club as their first by an academic press; it became a bestseller. His second book, "Sundown" (1934) is his most well known, an exploration of the disruption of the people and their society at the time of the oil boom, which also attracted criminal activities by leading whites in the county and state, including murder of Osage. In 1951 Mathews published a biography of E. W. Marland, noted oilman and governor of Oklahoma in the 1930s. His book "The Osages: Children of the Middle Waters" (1961) was a life work, preserving many collected stories and the oral history of the Osage.