Collage, a term derived from the French verb coller ("to paste"), is the technique of incorporating such materials as paper, cloth, foil, rope, newspaper, and other printed matter in an oil painting. Related to collage are the papiers colles (pasted paper) in which similar materials are combined in drawings. Pablo Picasso created the first collage in May 1912 (Still Life with a Caned Chair) and in September 1912 Georges Braque produced the first papier colle (The Fruit Dish). Containing nontraditional and intrinsically worthless materials, collages and papiers colles were intentional repudiations of the classical tradition of belle peinture, the definition of fine art as one consisting of fine materials. Although Picasso and Braque regarded their collages and papiers colles as independent art forms, these immediately proved to be the sources of major stylistic inventions in the development of Cubism.

During World War I the Dadaists advanced the concept of collage: in 1915 Jean Arp dropped pieces of paper onto a large sheet and pasted these pieces exactly where they fell. This first collage per se (without the addition of painting or drawing) became known as abstract collage. Max Ernst, working in the styles of both Dada and Surrealism, collaged pictorial material from old catalogs, medical texts, and steel engravings to produce often disquieting images. American collagists include Arthur Dove, Joseph Cornell, and Robert Rauschenberg.

Concurrent with their first experiments in collage and papiers colles, Braque and Picasso began to create sculptures, called assemblages, consisting of cardboard, string, wood, wire, and sheet metal. These three-dimensional collages are called assemblages. At the same time, the Italian futurists, far more radical in their rejection of traditional techniques and media, particularly Umberto Boccioni, advocated the use of as many as 20 heterogeneous materials in a single construction. Other notable assemblagists are the Russians Vladimir Tatlin and Kasimir Malevich and the Americans Louise Nevelson, Richard Stankiewicz, and John Chamberlain. Related to both collage and assemblage is decoupage, the decoration of generally utilitarian objects by completely covering them with cutout paper figures or patterns.