The mechanism of general anaesthetic action is poorly understood despite their widespread use. It is hoped that investigating the interaction of anaesthetics with lipid bilayers will help develop our understanding of how they work. We have recently demonstrated that we can resolve both the position of the anaesthetic molecule and the resultant effect on the lipid bilayer using neutron reflection from simple SAM supported floating membranes. In this proposal we will study the effects of lipophilicity of both GA and head group charging on the structure and inclusion of alcohol into the head group region.