The Semi-Slav variation of the Queen's Gambit leads to some of the most complex positions in chess theory. In brief, Black concedes space at the centre of the board in order to launch a counter-attack on the queenside. It is a favourite of Garry Kasparov, and recently has become extremely popular with younger champions such as Vishy Anand, Vladimir Kramnik, Vesselin Topalov, Gata Kamsky and Alexei Shirov. This book examines all aspects of the Semi-Slav, with the needs of the competitive player in mind. It includes all the recent development and many important games, accompanied by original analysis.