Baseball explores the history of organized baseball during the mid-twentieth century, examining the sport on and off the field and contextualizing its development as both sport and business. Steven P. Gietschier begins with the Great Depression, looking at how those years of economic turmoil shaped the sport and how baseball responded. Gietschier covers a then-burgeoning group of owners, players, and key figures—among them Branch Rickey, Larry MacPhail, Hank Greenberg, and Ford Frick—whose stories figure prominently in baseball's past and some of whom are still prominent in its collective consciousness.

Combining narrative and analysis, Gietschier tells the game's history while simultaneously exploring its politics and economics, including how the game confronted and barely survived the US's entry into World War II; how owners controlled the players; and how the business of baseball interacted with the federal government. He reveals how baseball handled the return to peacetime and the defining postwar decade, including the integration of the game, the demise of the Negro Leagues, the emergence of television, and the first efforts to expand into new markets. Gietschier considers much of the work done by biographers, scholars, and baseball researchers to inform a new and current history of baseball in one of its more important and transformational periods.