This book examines the life and work of the extraordinary Polish economist, Michal Kalecki. It discusses Kalecki's theory of the capitalist economy, and provides a thorough guided tour through his published works, including his important writings on the economics of underdeveloped countries. Kalecki's ideas received wide international recognition during the period when Keynesianism predominated in the economic landscape. In the early 1930s, Kalecki anticipated many aspects of the principle of effective demand that later John Maynard Keynes put forward in his General Theory of Employment, Interest and Money. This book commemorates Kalecki's originality and great contribution to economics. The book is co-authored by a former student of Kalecki. It includes original notes taken from Kalecki's courses, which up till now have never been published. This book is indispensable reading for all interested in the history of economic thought.