Horace Poolaw (1906-84) was an American Indian photographer who documented the life of his Oklahoma community of Kiowa Indians over five decades, from the 1920s to the 1970s. The National Museum of the American Indian in New York will run an exhibition of his work, from Aug. 9 through Feb. 15, 2015.

Mr. Poolaw's work—as seen in both the exhibit and a companion book, "For a Love of His People: The Photography of Horace Poolaw" (Yale University Press)—bears witness to a period of great change in the lives of his subjects,...