The Museum's collection of American paintings, sculpture, and works on paper contains approximately 1,000 works of art dating from the 18th century to 1960, with particular strength in the early 20th century. Museum founder Ralph Norton was keenly interested in representing the art of his own time as well as providing an understanding of the history of American art.

He acquired iconic paintings by George Bellows, Charles Demuth, Georgia O’Keeffe, John Marin, Robert Motherwell, and Charles Sheeler. He pursued sculpture by Gaston Lachaise, Theodore Roszak, and William Zorach among others. In anticipation of the Museum’s opening, Norton commissioned Paul Manship to create the sculpture — Diana and Actaeon — for the façade of the original building.

Significant acquisitions after Norton’s death in 1953 include the purchases of Stuart Davis’ 1932 painting, New York Mural, and Jackson Pollock’s 1945 canvas, Night Mist, and, a gift of 19 paintings from Elsie and Marvin Dekelboum in 2005.