The chicken is a foundational model for immunology research and continues to be a valuable animal for insights into immune function. In particular, the bursa of Fabricius can provide a useful experimental model of the development of B lymphocytes. Furthermore, an understanding of avian immunity has direct practical application since chickens are a vital food source. Recent work has revealed some of the molecular interactions necessary to allow proper repertoire diversification in the bursa while enforcing quality control of the lymphocytes produced, ensuring that functional cells without self-reactive Ig receptors populate the peripheral immune organs. Our laboratory has focused on the function of chB6, a novel molecule capable of inducing rapid apoptosis in bursal B cells. Our recent work on chB6 will be presented and placed in the context of other recent studies of B cell development in the bursa.