Monoclonal antibodies (MAbs) destined for use in drug-specific assays must meet specific binding criteria, and therefore require much more in the way of development than many protein-specific antibodies. This article describes one way to facilitate the development of well-characterized, high specificity MAbs. Essentially the same techniques have also been used for producing MAbs that are cancer markers and MAbs that are specific for infectious agents. Monoclonal antibody development, as in other endeavors, requires clearly defined goals and an examination of proposed methods to attain them. This has been succinctly stated by the phrase “Start with the end in mind.” Unfortunately, the vast majority of hybridoma development could be more appropriately described by Yogi Berra, “If you don’t know where you are going, you will wind up somewhere else.” In most laboratories, fusions are carried out with the goal of reducing the amount of cell culture and handling required and using the minimum amount of screening. Little or no consideration is given to ensuring that single clones are subjected to the screening tests. Under these conditions, it is little wonder that dozens of fusions can be carried out, each with the same result — no specific antibody found…