The mechanism that enables a protein to fold to its correct three-dimensional conformation—given only the information available from its sequence-has been a matter of intense investigation since Anfinsen’s classical experiment on the refolding of ribonuclease almost 40 years ago (1). The importance of turn sequences in the kinetic and thermodynamic aspects of protein folding remains a controversial point, although their role—especially forβ-turns—has been regarded as significant (i.e., 2–10). What role, if any, do turn sequences play in determining the native structures of proteins? For the experimentalist, this question is usually rephrased as: to what extent can substitution, insertion, and deletion be tolerated at turn positions before kinetic and/or thermodynamic properties are affected? It is indeed surprising how few experimental studies have been performed to carefully investigate the role of turns. To the theoretician, this question of the importance of turns revolves around the ability of computational studies to attempt to determine the propensity of isolated small peptides, as well as larger structures, to form turns. While much research has been conducted in this field, even here the answers remain uncertain.