In nature, the molecular-recognition ability of peptides and, consequently, their functions are evolved through successive cycles of mutation and selection. Using biology as a guide, it is now possible to select, tailor, and control peptide-solid interactions and exploit them in novel ways. Combinatorial mutagenesis provides a protocol to genetically select short peptides with specific affinity to the surfaces of a variety of materials including metals, ceramics, and semiconductors. In the articles of this issue, we describe molecular characterization of inorganic-binding peptides; explain their further tailoring using post-selection genetic engineering and bioinformatics; and finally demonstrate their utility as molecular synthesizers, erectors, and assemblers. The peptides become fundamental building blocks of functional materials, each uniquely designed for an application in areas ranging from practical engineering to medicine.