In 1900, Swedish design reformer and social theorist Ellen Key published The Century of the Child, presaging the coming century as a period of intensified focus and progressive thinking around the rights, development, and wellbeing of children. Taking inspiration from Key - and looking back through the twentieth century - this volume, published to accompany an exhibition at The Museum of Modern Art, examines individual and collective visions for the material world of children, from utopian dreams for the 'citizens of the future' to the dark realities of political conflict and exploitation. Surveying more than one hundred years of school architecture, clothing, toys, children's hospitals, nurseries, furniture, posters, animation and books, this richly illustrated catalogue illuminates how progressive design has enhanced the physical, intellectual and emotional development of children and, conversely, how models of children's play have informed experimental aesthetics and imaginative design thinking - engendering, in the process, reappraisals of some of the iconic names in twentieth-century design and enriching the unfolding narrative of modern design with other, less familiar figures.