The present invention relates generally to a method for the generation of a substantially homogenous population of undifferentiated cells. More particularly, the present invention relates to a method for isolating a substantially homogenous population of stem cells, and in particular, mammary stem cells (MaSCs). The MaSCs of the present invention are isolated on the basis of differential levels of proteins present on their cell surface. The MaSCs of the present invention are particularly useful as targets for identifying agents which modulate MaSC survival, self-renewal, proliferation and/or differentiation in both normal and diseased tissue such as, but not limited to, tumor tissue, and, also as source of tissue for the regeneration, replacement and/or augmentation of tissue damaged and/or lost after disease or injury.