Protein and peptide therapeutics score better than small-molecule therapeutics owing to their higher potency, greater specificity, and fewer immunological responses. Furthermore, they also have an advantage over gene therapy in terms of being safer since these involve a downstream regulation mechanism and do not alter the genetic machinery. Due to their unique advantages, there are currently more than 80 peptide drugs in the global market, with insulin and its analogs responsible for 50% of the peptide drug revenue. There are also 150 peptide drugs in the clinical pipeline and another 400-600 undergoing preclinical studies. Proteins and peptides are investigated for several therapeutic purposes, including cytokines, antibodies, enzymes, tumor antigens, and proapoptotic proteins/peptides. Although the market for protein-based therapeutics shows potential and is rapidly expanding, it is fraught with delivery challenges owing to the low oral bioavailability, low plasma stability, short circulation time in the biologic milieu, and inability to cross cell membranes. This special section, entitled "Nanotechnology-Based Delivery Strategies for Protein and Peptide Therapeutics," includes five mini-reviews providing deep insight into the advanced strategies for the effective delivery of proteins and peptides.