This dissertation is an inquiry into the political and intellectual currents of English Canadian left nationalism from the late 1960s through the 1970s. It investigates the reasons why left nationalism emerged as a major force in English Canadian left politics and explores the evolution of a neo-Marxist critique of both Canadian capitalism and Canada's relationship with the United States. Left nationalism represented a distinctive perspective and political agenda. Its vision was of a Canada divorced from the American-led capitalist world system. English Canadian left nationalism had a political manifestation in the Waffle movement and an intellectual manifestation in the New Canadian Political Economy. The dissertation demonstrates that the left nationalist interpretation of Canadian-American relations was not rooted in anti-Americanism, but in a radical politics of democratic socialism and anti-imperialism. Left nationalism was primarily the product of neo-Marxist thought, rather than a reaction to problems in American politics, society, and foreign policy. English Canadian left nationalists were disruptors who, unlike their New Nationalist contemporaries, did not advance a program of capitalist or social democratic reform. The left nationalists were determined to replace capitalism with democratic socialism; without socialism, there could be no Canadian independence. Left nationalists sought to end Canada's colonial status in the declining American empire, viewed the preservation of Canada's resources as imperative to the country's long-term prosperity, and advanced neo-Marxism in the academy and in the universities. The dissertation interrogates internal debates within the New Democratic Party over how to respond to the problem of American dependency; the rise and fall of the Waffle movement; the left nationalist response to crises in Canadian-American relations during the late 1960s and early 1970s; and the establishment of the New Canadian Political Economy, left nationalism's most enduring legacy.