For Marxists, imperialism is the highest stage of capitalism. Critical analysis of imperialism has been a feature of Marxist throughout the twentieth century. The conceptualising and theorising of imperialism by Marxists has evolved over time in response to developments in the global capitalist economy and in international politics. Murray Noonan here provides the first complete analysis of Marxist theories of imperialism in over two decades. Presenting three phases of imperialist theories, he analyses and compares ”Classical”, ”Neo” and ”Globalisation-era” Marxist theories of imperialism. The book moves chronologically, tracking the origins of imperialism theorised by J.A. Hobson at the beginning of the twentieth century up to the present day. He critically identifies and engages with a new ”Globalisation-era” phase of Marxist imperialism theory. Through a detailed scholarly analysis of the history and evolution of these theories, Noonan offers vital new perspectives on imperialist theory and its relevance and application in the twenty-first century.