Systematical studies will be performed on the structural behaviour of lipid compounds of the type present in important biological systems such as membranes. Detailed single crystal analyses will be performed whenever possible. In addition systems of such compounds will be investigated by powder diffraction and low-angle scattering techniques as well as with other physical methods, even in cases where only partial order exists. The investigation will provide basic knowledge required for an understanding of the molecular architecture of biological systems containing ordered or partly ordered lipid molecules.