Three subsets of mature B cells exist in mice: B-1, follicular and marginal zone B cells. The recruitment of newly formed transitional B cells into these compartments depends on signals emanating from the B-cell antigen receptor, possibly in response to (self-)antigen recognition. Recent evidence suggests that peripheral B-cell fate is controlled by B-cell antigen receptor signal strength, acting in concert with the cytokine B-cell activating factor. Other work indicates that peripheral B-cell development is orchestrated by a complex network of transcription factors, which drive B-cell subset differentiation, at the same time preventing mature B cells from undergoing trans-differentiation or premature terminal differentiation.