The present invention relates to a method for preparing a peptide having a stable, internally constrained alpha-helical, beta-sheet/beta-turn, 3.sub.10-helical, or pi-helical region and a method of stabilizing an alpha-helical, beta-sheet/beta-turn, 3.sub.10-helical, or pi-helical region within a peptide structure. The resulting peptides and methods of using them are also disclosed.