McGerr's A Fierce Discontent: The Rise and Fall of the Progressive Movement in America, 1870-1920 is a study of the Progressive Era. The author tries to make sense of the many impulses and agendas that defined the Progressive Era. He locates the source of the movement in the impulses and anxieties of the middle class at the time and states that:
Progressivism was the way in which these Victorian men and women came to answer the basic questions of life . . . What is the individual? What is the relationship between the individual and society? (xiv).
In other words, Progressivism was led by middle-class people reacting to the excesses of the Gilded Age and trying to determine the extent to the which the individual bore responsibility for his or her society and was connected to the larger society. He traces the ways in which the Victorian middle class took on four specific battles: to change big business, change people, put an end to class conflict, and deal with segregation. The author focuses on both the larger and more apparent political battles the Progressives waged but also the smaller, more domestic questions they wrestled with (such as divorce and gender roles).
The author recognizes the limits of Progressivism, including its unwillingness to totally restructure the economy and its acceptance of segregation. As the author writes, "the Progressives turned to segregation as a way to halt dangerous social conflict" (page 183). In other words, the Progressives saw segregation as a way to protect groups such as African-Americans and Native Americans from destruction.
McGerr's argument is based on a wide range of sources, including both public acts and laws, the writings of private individuals, and cultural sources, such as reporting on sports. The author states that it's important to understand the Progressive Era because it set the stage for the political battles that would be waged for the rest of the 20th century.