The present invention relates to compositions and methods for culturing stem cells, particularly embryonic stem cells. Specifically, the invention relates to a culture medium that supports proliferation of substantially undifferentiated stem cells, while maintaining potency of the cells. An an embodiment, the culture medium is defined and supports proliferation of substantially undifferentiated embryonic stem cells in essentially serum free and feeder cell free conditions. Compositions for making the medium and methods using the culture medium are also provided.
