Experimental evidence contradicts the simplistic view that during development all B cells expressing non autoreactive antigen receptors on the cell surface are selected into the mature B-cell pool. While allelic exclusion, clonal selection and affinity maturation continue to define the mainstream notions of B-cell development and selection, new evidence is redefining our understanding of these processes. Receptor editing replaces functional B-cell receptors by secondary immunoglobulin gene rearrangements, a process that can play roles in both immune tolerance and immune response. In addition, editing can rescue cells that would otherwise fail positive selection. We focus here on our studies indicating that the functional competence of the B-cell antigen receptor complex plays a central role in the fate of developing B cells and their antigen receptor genes.