De Stijl is a Dutch artistic movement founded in 1917. The De Stijl consisted of artists and architects. In a narrower sense, the term De Stijl is used to refer to a body of work from 1917 to 1931 founded in the Netherlands. Proponents of De Stijl advocated pure abstraction and simplified form for its own sake, as a means of expression, rather than solely as an aesthetic effect.

The works of De Stijl would influence the Bauhaus style and the international style of architecture as well as modern design. Its members included the painters Piet Mondrian, Georges Vantongerloo, and Theo van Doesburg (who also worked with J.J.P. Oud), and the architects Gerrit Rietveld, Robert van ‘t Hoff, and Cornelis van Eesteren. The movement had its roots in the Amsterdam-based group of young artists who, from about 1908 onwards, came together around Pierre Cuijpers and Wassily Kandinsky. As a counterbalance to the Constructivism of Vladimir Tatlin, they advocated an art based on absolute abstraction, operating within a strict geometric framework.

In their quest for simplification, Mondrian and the De Stijl artists reduced art to its basic visual components: horizontal and vertical lines and rectangles of primary colors, plus black and white. The only exceptions were the horizontally-oriented oval forms associated with Piet Mondrian’s personal style, or the use of a diagonal line. De Stijl artists would frequently reduce the number of colors used in their work to three, or sometimes four. The only non-primary colors allowed were those created by mixing two primaries; secondary colors and tertiary colors were not allowed.

The De Stijl aesthetic was subsequently adopted as the style of architecture known as the International Style. However, its geometric purity was rarely achieved in practice, and many of the buildings constructed in this style were actually quite different from the De Stijl ideal. Nevertheless, the influence of De Stijl was evident in many areas of design, particularly in the fields of architecture and industrial design.