The article discusses the diversification of phage-displayed peptide libraries using noncanonical amino acids (ncAAs) and chemical modifications. Phage display is a powerful technique for generating and screening peptide libraries, but traditional methods are limited to canonical amino acids. Recent advances in genetic code expansion and chemical methods have enabled the incorporation of ncAAs with novel reactivities into phage libraries, enhancing their potential for therapeutic applications. The review covers the use of orthogonal genetic code expansion to introduce ncAAs into phage-displayed peptides, as well as chemical post-translational modifications that allow for the addition of diverse functional groups. These methods have expanded the chemical diversity of phage libraries, enabling the identification of peptides with improved binding properties and therapeutic potential. The article also highlights the development of amber-obligate phage libraries, which rely on specific ncAAs for phage production, and the application of these libraries in identifying ligands for various targets. Additionally, the review discusses the challenges and limitations of current methods, including the need for improved stability and efficiency in ncAA incorporation. Overall, the integration of ncAAs and chemical modifications into phage libraries represents a significant advancement in the field of peptide therapeutics, offering new opportunities for drug discovery and development.The article discusses the diversification of phage-displayed peptide libraries using noncanonical amino acids (ncAAs) and chemical modifications. Phage display is a powerful technique for generating and screening peptide libraries, but traditional methods are limited to canonical amino acids. Recent advances in genetic code expansion and chemical methods have enabled the incorporation of ncAAs with novel reactivities into phage libraries, enhancing their potential for therapeutic applications. The review covers the use of orthogonal genetic code expansion to introduce ncAAs into phage-displayed peptides, as well as chemical post-translational modifications that allow for the addition of diverse functional groups. These methods have expanded the chemical diversity of phage libraries, enabling the identification of peptides with improved binding properties and therapeutic potential. The article also highlights the development of amber-obligate phage libraries, which rely on specific ncAAs for phage production, and the application of these libraries in identifying ligands for various targets. Additionally, the review discusses the challenges and limitations of current methods, including the need for improved stability and efficiency in ncAA incorporation. Overall, the integration of ncAAs and chemical modifications into phage libraries represents a significant advancement in the field of peptide therapeutics, offering new opportunities for drug discovery and development.