As the first great Jewish player in the major leagues and the first African American to play major-league baseball during the twentieth century, respectively, Hank Greenberg and Jackie Robinson are forever linked because of the barriers they encountered, the discrimination they endured, the athletic gifts they exhibited, and especially the courage and dignity they displayed. Both suffered ridicule and abuse as they participated in the national pastime. Nevertheless, each excelled. Greenberg became one of the preeminent sluggers of the 1930s and 1940s who took a break from baseball to serve in the war. Robinson, from the mid-1940s into the following decade, helped bring back speed and a thinking man’s approach to the game, both of which had largely been discarded for a generation. Two Pioneers presents these remarkable players’ experiences while competing in a nation that was deeply divided on social issues such as anti-Semitism and racism. Both men earned nearly as much attention off the field as they did on it. Greenberg called into question the idea of a “master race” as Adolf Hitler rose to power and gained supporters all over the world. Likewise, Robinson contested racial notions regarding the supposed inferiority of people of African ancestry, even though segregationists proved determined to maintain social barriers separating blacks and whites. It is only fitting that when Robinson finally crossed baseball’s color line, Greenberg was one of the first players to welcome him publicly. Robert Cottrell’s well-researched work shows how two baseball superstars became important figures in the civil rights crusade to ensure that all Americans, no matter their religion or race, are given equal opportunity.