In 1958, Lester B. Pearson became head of Canada’s Liberal Party, becoming Leader of the Official Opposition in Prime Minister John Diefenbaker’s Progressive Conservative government. While Pearson became Prime Minister himself in 1963, Saskatchewan reporter and author Robert Moon contends that Pearson’s five years as Opposition Leader were his “severest test” in federal politics (1). In this volume, Moon recounts Pearson’s years as Opposition Leader, as well as the changing political currents that eventually pushed Pearson into the role of Prime Minister (and Diefenbaker into a second stint as Opposition Leader). With journalistic precision, he weaves together quotations from key figures with contextual explanations to lay out Pearson’s role in Canadian federal politics in the late 1950s and early 1960s.