This term, first coined by Harold Rosenberg, refers to the dribbling, splashing or otherwise unconventional techniques of applying paint to a canvas. Connected to the Abstract Expressionist movement, but more precise in its meaning, Action Painting believes in the expressive power held in the actual act of painting as much as in the finished product. Rosenberg defined the notion of the canvas as seen by the artists in this movement as being 'not a picture but an event'. 

Jackson Pollock was the leading figure of the movement, employing the 'drip' technique to create his vast paint splattered canvases. There is some debate as to how much he left to chance and how much the finished product reflected his original intentions, but the power of his works lies in their energy and sheer drama.

Other artists produced Action Paintings often employing quite unconventional techniques. The British painter William Green, for example, rode a bicycle over his canvas, while one of the Gutai Group in Japan painted with his feet as he hung from a rope. Critics were divided over the worth and purpose of this movement as for every Pollock there were numerous examples of over-indulgence and derisive imitations. In retrospect, however, it stands as an important aspect of Abstract Expressionism and it can be seen as a precursor to many later techniques such as Spin Art.