It is possible to "stretch" a liquid and, when suitably prepared, liquids are capable of sustaining substantial levels of tension, often for significant periods of time. These negative pressure states are metastable but can last for days - long enough for substantial experimental investigation. This volume is a review of recent and current research into the behaviour of liquids under negative pressure. Part I deals with the thermodynamics of stretched liquids. Part II discusses the physical and chemical behaviour of liquids under negative pressure. Part III contains papers on the effect of negative pressure on the solidification of a liquid. Part IV is devoted to stretched helium and Part V discusses cavitation in various stretched liquids. Part VI deals with the effect of foreign substances on cavitation.