Nanostructured materials are receiving increased attention from both academia and industry. For example, the fundamental understanding of fiber formation by peptides and proteins both is of interest in itself and may lead to a range of applications. A key idea here is that the folding and subsequent supramolecular assembly of the monomers can be programmed within polypeptide chains. Thus, with an understanding of so-called sequence-to-structure relationships for these peptide assemblies, it may be possible to design novel nanostructures from the bottom up that exhibit properties determined by, but not characteristic of, their component building blocks. In this respect, the α-helical leucine zipper presents an excellent place to start in the rational design of ordered nanostructures that span several length scales. Indeed, such systems have been put forward and developed to different degrees. Despite their apparent diversity, they employ similar assembly routes that can be compiled into one basic methodology. This chapter gives examples and provides methods of what can be achieved through leucine zipper-based assembly of fibrous structures.