From the summer of 1933 to the fall of 1934, more than 38 million fairgoers visited a 3-mile stretch along Lake Michigan, home to Chicago's second World's Fair. Millions more experienced the Century of Progress International Exposition through newspaper and magazine articles, newsreels, and souvenirs. Together, all marveled at the industrial, scientific, consumer, and cultural displays, many of which were housed in fifty massive and colorful exhibition halls, the largest architectural project realized in the United States during the Great Depression. In the richly illustrated Building a Century of Progress, Lisa D. Schrenk explores the pivotal role of the 1933 Chicago World's Fair in modern American architecture. She recounts how the exposition's architectural commission promoted a broad definition of modern architecture, not relying on purely aesthetic characteristics but instead focusing on new design solutions. The fair's pavilions incorporated recently introduced building materials such as masonite and gypsum board; structural innovations (for example, the first thin-shell concrete roof and the first suspended roof structures built in the United States); and new construction processes, most notably the use of prefabrication. They also featured curiosities like the giant, constantly operating mayonnaise maker and the glass-walled House of Tomorrow, which had no operable windows. Schrenk shows how the halls' designs reflected cultural and political developments of the period, including the expanding relationships between science, industry, and government; the rise of a corporate consumer culture; and the impact of the Great Depression. Many of the designs provoked intense responses from critics and other prominent architects, including Frank Lloyd Wright and Ralph Adams Cram, fueling heated debates over the appropriate direction for architecture in the United States. Demonstrating the rich diversity of progressive American building design seen at the fair, Building a Century of Progress captures a crucial moment in American modernism. Lisa D. Schrenk is assistant professor of architecture and art history at Norwich University and former education director of the Frank Lloyd Wright Home and Studio Foundation.