The designation Abstract Expressionism [more] encompasses a wide variety of postwar American painting through which the U.S. first became the center of the avant-garde. Critic Clement Greenberg, a major proponent of the New York School (another name for American artists working in this manner), preferred the term Painterly abstraction in order to describe the formal qualities of this painting: its lack of figuration and loose brushwork. The related term Action Painting was coined by critic Harold Rosenberg to refer to the gestural act of painting, which he considered the artist’s unconscious outpouring or enactment of some personal drama. The expressive aspect of this art has been linked to the subjective heroism of earlier forms of Expressionism as well as to the Surrealist technique of automatic writing. The influence of Surrealists and other artists who fled Europe for New York in the late 1930s and the 1940s was integral to the development of Abstract Expressionism.

In the late 1940s and early 1950s Jackson Pollock, considered the foremost Abstract Expressionist, placed his canvases on the floor to pour, drip, and splatter paint onto them and to work on them from all sides, which set him apart from the tradition of vertical easel painting. Other painters who worked in gestural modes were William Baziotes, Willem de Kooning, Arshile Gorky, Adolph Gottlieb, Philip Guston, Franz Kline, and Robert Motherwell. Another component of the Abstract Expressionist school used large planes of color, often to evoke invisible spiritual states. These Color-field painters include Barnett Newman and Mark Rothko. Their lead was followed by Helen Frankenthaler, Morris Louis, and others who poured thin acrylic stains onto unprimed canvases in order to make color an inherent part of their paintings. The term Abstract Expressionism has also been applied to the work of sculptors such as Herbert Ferber and David Hare.