In February 1899, the Committee of Physical Culture of the Chicago Public School Board approved an intensive "anthropometric" study of all children enrolled in the city's public schools. The study was a detailed attempt to measure the height, weight, strength, lung capacity, hearing, and general fitness of Chicago's student population. Through 1899 and 1900, thousands of Chicago's primary, grammar, and high school students had their bodies closely scrutinized, measured, weighed, tested, and, in a few cases, diagrammed. What the School Board members wanted to know was the "fitness" of the student body. Were Chicago public school students--many recently arrived immigrants from eastern and southern Europe--vital and vigorous children who could become energetic modern workers and citizens? In this article, the author examines how the practice of body-building, of educating and cultivating the ideal type of body, was imbricated within a variety of social and political anxieties that absorbed many Americans, particularly members of the middle class, in the last decade of the nineteenth century and first decades of the twentieth century. (Contains 4 figures and 104 footnotes.)