Amphiphilic layers play essential roles in the behaviour of a great variety of disperse systems such as micelles, microemulsions and vesicles. They can also exist as isolated mono- or bilayers, or constitute extended liquid crystalline structures. Although the properties of these different systems may at first sight seem unrelated, theoretical interpretations of them depend on several common concepts. This was the reason for bringing together scientists working in this area for the International Winter School on the Physics of Amphiphilic Layers, which was held at Les Houches, 10-18 February, 1987. The topics treated in the proceedings volume are mono- and bilayers, interactive forces between layers (with