Dendritic cells (DC) are key regulators of the immune system. They are capable of stimulating lymphocytes to generate potent cell-mediated and humoral immune responses against pathogens and tumor cells. DC not only activate lymphocytes, but can also educate T cells to tolerate self-antigens, thereby minimizing autoimmune reactions. Another peculiarity of the DC system is the large variety of subsets described, both in the human and in the mouse, according to surface phenotype and organ distribution. Different protocols have been developed to differentiate DC from total mouse bone marrow in vitro. Here, we describe the isolation of a specific DC progenitor population, referred to as preimmunocytes, and document protocols for their differentiation into various DC subsets.