The major theme of American childhood in the 20th century has been the rise and then the beginning decline of modern childhood. The term "modern childhood" refers to a particular constellation of adult attitudes and institutional arrangements, the heart of which is the belief that children should occupy a world of their own, separate from the world of adults. Three factors led to the rise of this idea in the 19th century: the increased preoccupation with the nature and needs of children, the belief that adulthood was becoming so complex that it required a long apprenticeship, and a family structure that gave women primary responsibility for childrearing. Much of the impetus for child welfare legislation in the first half of the 20th century came from women with genuine concern for the young. Other political and economic motives for this legislation meant that it received meager funding and produced uneven results. Modern childhood became firmly established in the child-centered suburban homes created by post World War II prosperity. The decline of modern childhood began in the 1950s and continued over the next decades due to changes in women's economic roles, the structure of families, and the mass media. (Author/CB)