The present invention relates to an improved method that permits the differential isolation of mouse mammary stem cells and colony forming cells (CFCs). The method involves depletion of non-epithelial cells from freshly dissociated mouse mammary tissue by incubation with an antibody composition containing antibodies specific for CD45, Ter119, CD35 and optionally CD140a. After formation of conjugates between the non-epithelial mammary cells and the antibodies specific for CD45, Ter119, CD35 and optionally CD140a, the cell conjugates are removed and the remaining epithelial cells are then incubated with an antibody composition containing antibodies specific for CD24 and CD49f. After formation of conjugates between the epithelial cells and the antibodies specific for CD24 and CD49f, the mouse mammary stem and the luminal-restricted CFC cells can be differentially isolated. The invention also relates to kits for carrying out this method and to the cell preparations prepared by this method.