A study of the evolution of American women's clothing, ""When the Girls Came Out to Play"" traces the history of modern sportswear as a universal style that broke down traditional gender roles. Patricia Warner shows how this profound cultural shift, which did not reach fruition until World War II, originated during the previous century with the gradual expansion of socially acceptable physical activity for women. Behind this development was a growing interest in sports and exercise that was further nurtured by the establishment of schools of higher education for women. The participation of women in athletic pursuits previously reserved for men began with the relatively genteel sports of croquet and tennis. With the founding of women's colleges, these ""ladylike"" games were supplemented by more vigorous activities and competitive team sports, from gymnastics to swimming to basketball. At first, Warner points out, women literally had nothing to wear for these activities. Whereas such fashionable attire as corsets, petticoats, hats, and gloves could be worn while playing outdoor lawn games, more strenuous athletic endeavours required less physically restrictive clothing. Even so, change came only gradually, as women's colleges, shielded from public scrutiny and prying male eyes, permitted the adoption of looser, more comfortable apparel for physical education. Many of these new outfits featured trousers, garments considered taboo for women, though they often remained hidden beneath voluminous skirts. Over time, however, the practicality and versatility of such clothing led to social acceptance, laying the foundation for the emergence of the now ubiquitous yet distinctly American style known as sportswear. Although, we take it for granted, Warner observes, this is the first time in the history of the world that such universality has existed in clothing, and it has lasted now for well over half a century - in itself a marvel, considering the speed of fashion change in an era of instant messages and images.