Phage display is based on expressing recombinant proteins fused to a phage coat protein. The genetic information encoding for the displayed molecule is physically linked to its product via the displaying particle. With phage display, tailor-made proteins (fused peptides, antibodies, enzymes, DNA-binding proteins) may be synthesized and selected to acquire the desired catalytic properties or affinity and specificity of binding. This unit provides protocols for the construction of, and selection from antibody phage display libraries, together with useful approaches for the analysis of phage antibodies. This unit focuses on the construction of immune libraries where the sources for antibody genes are spleens of immunized mice and the isolation and initial characterization of single-chain antibodies (scFvs) from such libraries.