This article aims at contributing to current debates on the ‘new imperialism’ by presenting the main results of a reading of Marx’sCapitalin light of his writings on colonialism, which were unknown in the early Marxist debate on imperialism. It aims to prove that, in his main work, Marx does not analyse a national economy or – correspondingly – an abstract model of capitalist society, but a world-polarising and ever-expanding system. This abstraction allows the identification of the laws of development of (...) capitalism and its antagonisms, and reflects the tendency of the capital of the dominant states, by making permanent recourse also to methods of so-called ‘primitive accumulation’, to expand and increase the exploitation of workers worldwide, and, at the same time, the cooperation between them. What, for Marx, was later defined as imperialism is the concrete form of the process of ‘globalisation’ of the capital of the dominant states. With the development of his analysis, Marx became increasingly aware of the economic and political consequences of imperialism. In his activity within the First International, with regard to the question of Irish independence, he affirmed the fundamental importance of building a real solidarity between class struggles in imperialist countries and anti-colonial resistance in colonised and dependent countries. His examination of imperialism and internationalist perspective were downplayed, denied, if not completely reversed in the interpretation and systematisation of his thought by reformist leaders within the Second International. In their attempt to react against this tendency and develop an analysis and a political strategy adequate to the new phase of generalised imperialist expansion, increased inter-imperialist rivalries and rising anti-colonial resistance, Rosa Luxemburg and Lenin reaffirmed the centrality of the critique of imperialism at the economic and at the political levels. Even if they were partially unaware of this, they thus developed and expanded on some aspects already present in Marx’s work. (shrink)