Solid supported membrane systems have been established as biomimetic architectures, which allow for the systematic investigation of various membrane-related processes. Especially tethered bilayer lipid membranes have been a successful concept. They consist of a lipid bilayer that is covalently anchored to a solid substrate through a spacer group. The submembrane part, which is defined by the spacer group, is important especially for the biological activity of incorporated membrane proteins. Anchor lipids with different spacer and anchor groups have been synthesized, and the resulting membrane structures have been investigated by neutron reflectivity. The different molecular architectures had a significant effect on both the amount of water incorporated in the spacer region and the electrical properties of the bilayer. A detailed understanding of the structure-function relationship allows for an optimized design of the molecular architecture with respect to possible applications, for example an optimized protein incorporation.