Publisher Summary This chapter discusses the formation of prebiotic peptides. Fox and Harada proposed melts of dried amino acids to form peptides. Another approach to prebiotic peptide formation is the use of condensation agents to facilitate the reactions between amino acids. The substances included cyanamides, cyanates, trimetaphosphate, ATP, GTP, CTP, UTP, linear and cyclic inorganic polyphosphates, and imidazoles. Under assumed hydrothermal vent conditions, amino acids can also condense to peptides, but this scenario would be restricted to specific locations in the deep sea and especially high partial pressures of carbon monoxide. A further possibility is peptide formation on the surface of minerals such as clays, silica, and alumina. The salt-induced peptide formation (SIPF) reaction is a special case among the many proposals for peptide formation under primordial Earth conditions. It allows for peptide formation in aqueous solution directly from amino acids or from amino acids and short peptides, as long as sodium chloride, Cu(II) ions, and thermal energy are available.