The successful transition of hemopoietic progenitors through the process of lineage commitment and differentiation relies on the precise orchestration of events in gene activation and repression. Our earlier studies on this developmental system have identified the Ikaros family of DNA binding factors. We have shown that these proteins impact the early commitment steps into the hemopoietic and lymphoid lineages and are critical regulators of proliferation in mature T and B cell lymphocytes. We are currently focused on the molecular mechanisms by which these factors effect their function in differentiation. We have recently shown that Ikaros and family members form distinct chromatin remodeling complexes in lymphocytes. The focus of our future research is to delineate the role and regulation of these remodeling complexes in the process of lineage determination and proliferation by a series of biochemical and genetic approaches.