Interferons have effects on many facets of immune system development, maturation, and function. B cells are a target for the interferons, causing alterations in cell differentiation and gene expression. However, production of interferons by B cells has not been widely studied. In this review I will discuss the limited literature on B-cell interferon production. In addition I will describe results obtained from a transgenic model in which interferon-γ production has been targeted to the B-cell compartment. In this animal, B-cell development is blocked, reflecting the deleterious effects that aberrant expression of interferon can have on this cell population.