Here, we describe a protocol for using the ADLib (Autonomously Diversifying Library) system to rapidly generate specific monoclonal antibodies using DT40, a chicken B-cell line that undergoes constitutive gene conversion at both light- and heavy-chain immunoglobulin loci. We previously developed the ADLib system on the basis of our finding that gene conversion in DT40 cells was enhanced by treatment of the cells with a histone deacetylase inhibitor, trichostatin A (TSA). TSA treatment evolves a diversified library of DT40 cells (ADLib), in which each cell has different surface IgM specificity. Antigen-specific DT40 cells are selected from ADLib using antigen-conjugated magnetic beads, and their specificity can be examined by various immunological assays, using culture supernatant containing secreted IgM. The whole process from selection to screening can be completed in about 1 week. Thus, the ADLib system will accelerate biological studies, including drug discovery and design.