Phage display has proven to be a powerful enabling technology in genomics and drug development. The directed evolution of proteins can be engineered for specific properties and selectivity. It provides an approach for the engineering of human antibodies, as well as protein ligands, and for such diverse applications as arrays, separations, and drug development. The use of phage display in screening for novel high-affinity ligands and their receptors has been useful in functional genomics and proteomics. Display methods promise to have benefit in the development of therapeutics targeting many different disorders, including cancer, AIDS, autoimmune and other diseases.