Despite being among the most important books of the last 150 years, Karl Marx's Capital represents an incomplete project. In this new book, renowned scholar Marcello Musto aims to reconstruct the development of Marx's critique of political economy in the light of newly available notebooks - published in the recent German edition of Marx's complete writings (Marx-Engels-Gesamtausgabe) to provide the fullest account yet of the formation of Marx's thought. Through the intimate study of these notebooks, Musto revives debate on Capital - a work that has inspired and guided generations of people looking to change the world. Indeed, on the 150th anniversary of its publication, Capital's continuing relevance is clear, with economists and political activists turning to its lessons in the wake of the international financial crisis. The Formation of Marx's `Capital' will also carefully consider some of the most important Marxist debates of the twentieth century. Did Engels oversimplify Marx? How limiting are Marxist-Leninist readings? And is it possible to produce a new reading of Marx for our time? Musto's analysis offers a distinctive account of the genesis of Marx's thought, with important implications for Marxist studies but also for the refounding of critical thought that aims to transform the present.