Characterized by an unusual variety and range of materials, Karel Appel found great flexibility and experimentation in the expressive medium of collage. Paper and cardboard fragments, newspaper clippings, and other found objects enter into a lively dialogue with his powerful, animalistic formations in watercolor, gouache, or crayon. For the first time, Appel's collages from the late 1950s and 1960s are presented in a nearly complete catalog. This publication reevaluates this particularly productive period and explores the works in the context of Nouveau Réalisme, taking into account new research approaches. With a further focus on the topic of collage, the book examines how Appel adopted this technique in his unique compositions.