Book excerpt: This book covers strategies to improve cell permeability, intestinal permeability, and metabolic stability, which are the typical liabilities associated with cyclic peptides, to enhance protein-protein recognition, and to build upon nature’s cyclic peptides and macrocycles. Chapters also cover key peptide screening and display strategies, as well as important synthetic approaches towards cyclic and helical peptides. Cyclic peptides have become of significant importance as chemical tools in biology and drug discovery, since this class of chemicals has become a credible alternative source of new drug leads on par with traditional small molecules. As a part of the Methods in Molecular Biology series, this collection includes the kind of detail and implementation advice to aid researchers in the field. Authoritative and cutting-edge, Cyclic Peptide Design serves as a critical resource and go-to reference for researchers within the pharmaceutical industry, as well as scientists and students in the bioorganic, medicinal, and natural product chemistry fields.