Pierre Elliott Trudeau – radical progressive or unavowed socialist? Christo Aivalis argues that although Trudeau found key influences and friendships on the left, he was in fact a consistently classic liberal, driven by individualist, capitalist principles. Trudeau’s legacy is still divisive. Most scholars portray Trudeau’s ties to unions and the Cooperative Commonwealth Federation as either evidence of communist affinities or as being at the root of his reputation as the champion of a progressive, modern Canada. The Constant Liberal traces the charismatic politician’s relationship with left and labour movements throughout his career. Trudeau worked with leftists in the 1950s to oppose right-wing Quebec premier Maurice Duplessis but against them as prime minister when workers and progressives were seen as obstacles to higher corporate profit margins. While numerous biographies have noted the impact of Trudeau’s engagement with the left on his intellectual and political development, this comprehensive analysis is the first to showcase the interplay between liberalism and democratic socialism that defined his world view – and shaped his effective use of power. The Constant Liberal suggests that Trudeau’s leftist activity was not so much a call for social democracy as a warning to fellow liberals that lack of reform could undermine liberal-capitalist social relations.