This important new book - the first of its kind - provides a detailed analysis and critical appraisal of the neo-Ricardian Keynesians and the post Keynesians. After placing them in the context of modern schools of macroeconomics, it discusses their contributions including the neo-Ricardian synthesis of Sraffa's ideas on the heterogeneity of capital goods and Keynes's ideas on effective demand, and the post Keyensian analysis of the role of historical time, money and uncertainty in Keynes's work. In conclusion, it suggests a synthesis of their views which could be seen as a starting point for an important challenge to mainstream economics.