"Conditional Design" is the name of a new design ethos formulated by graphic designers Luna Maurer, Jonathan Puckey and Roel Wouters, and artist Edo Paulus. It espouses a working method that involves drawing up arbitrary constraints and rules of play, fostering both a strongly collaborative spirit and unpredictable end results. Conditional Design provides beautifully simple ideas for open, collaborative processes in art and design. Its workbook format organizes the material step by step, and the publication as a whole provides exciting ways for others--groups of children as well as artists and designers--to apply the method themselves. In accompanying essays, Andrew Blauvelt elaborates on the implications of such processes for art and design, and Koert van Mensvoort describes how Conditional Design could form the basis for the design and organization of the city of Zhiango, China, in 2050.