This third edition summarizes the most important areas of Cell-Penetrating Peptides (CPP) research. Chapters are divided into three parts detailing the historical background of CPP, the classifications of the available CPPs, approaches for prediction of novel CPPs, methods for studies of "naked" CPPs, and a brief summary of functionality issues of CPPs, both in vitro and in vivo. Written in the format of the highly successful Methods in Molecular Biology series, each chapter includes an introduction to the topic, lists necessary materials and reagents, includes tips on troubleshooting and known pitfalls, and step-by-step, readily reproducible protocols. Authoritative and cutting-edge, Cell Penetrating Peptides: Methods and Protocols, Third Edition aims to be a useful practical guide to researches to help further their study in this field.