Crystalline arrays of protein or glycoprotein subunits forming surface layers (S-layers) are the most common outermost envelope components of prokaryotic organisms (archaea and bacteria). The wealth of information on the structure, chemistry, genetics, morphogenesis, and function of S-layers has revealed a broad application potential. As S-layers are periodic structures, they exhibit identical physicochemical properties for each molecular unit down to the subnanometer level and possess pores of identical size and morphology. Many applications of S-layers in nanobiotechnology depend on the ability of isolated subunits to recrystallize into monomolecular lattices in suspension or on suitable surfaces and interfaces. S-Layer lattices can be exploited as scaffolding and patterning elements for generating more complex supramolecular assemblies and structures, as required for life and nonlife science applications.