The World as Will and Representation (WWR; German: Die Welt als Wille und Vorstellung, WWV), sometimes translated as The World as Will and Idea, is the central work of the German philosopher Arthur Schopenhauer. The first edition was published in late 1818, with the date 1819 on the title-page. A second, two-volume edition appeared in 1844: volume one was an edited version of the 1818 edition, while volume two consisted of commentary on the ideas expounded in volume one. A third expanded edition was published in 1859, the year prior to Schopenhauer's death. In 1948, an abridged version was edited by Thomas Mann.

In the summer of 1813, Schopenhauer submitted his doctoral dissertation—On the Fourfold Root of the Principle of Sufficient Reason—and was awarded a doctorate from the University of Jena. After spending the following winter in Weimar, he lived in Dresden and published his treatise On Vision and Colours in 1816. Schopenhauer spent the next several years working on his chief work, The World as Will and Representation. Schopenhauer asserted that the work is meant to convey a "single thought" from various perspectives. He develops his philosophy over four books covering epistemology, ontology, aesthetics, and ethics. Following these books is an appendix containing Schopenhauer's detailed Criticism of the Kantian Philosophy.

Taking the transcendental idealism of Immanuel Kant as his starting point, Schopenhauer argues that the world humans experience around them—the world of objects in space and time and related in causal ways—exists solely as "representation" (Vorstellung) dependent on a cognizing subject, not as a world that can be considered to exist in itself (i.e., independently of how it appears to the subject's mind). One's knowledge of objects is thus knowledge of mere phenomena rather than things-in-themselves. Schopenhauer identifies the thing-in-itself—the inner essence of everything—as will: a blind, unconscious, aimless striving devoid of knowledge, outside of space and time, and free of all multiplicity. The world as representation is, therefore, the "objectification" of the will. Aesthetic experiences release a person briefly from his endless servitude to the will, which is the root of suffering. True redemption from life, Schopenhauer asserts, can only result from the total ascetic negation of the "will to life". Schopenhauer notes fundamental agreements between his philosophy, Platonism, and the philosophy of the ancient Indian Vedas.

The World as Will and Representation marked the pinnacle of Schopenhauer's philosophical thought; he spent the rest of his life refining, clarifying, and deepening the ideas presented in this work without any fundamental changes. The first edition was met with near-universal silence. The second edition of 1844 similarly failed to attract any interest. At the time, post-Kantian German academic philosophy was dominated by the German idealists—foremost among them G. W. F. Hegel, whom Schopenhauer bitterly denounced as a "charlatan". It was not until the publication of his Parerga and Paralipomena in 1851 that Schopenhauer began to see the start of the recognition that had eluded him for so long.