In vitro culture of whole mouse embryos enables the maintenance of growth and morphogenesis of postimplantation embryos outside the uterine environment. This technological advent facilitates the observation of the development of embryos in real time whereby cell lineage and tissue morphogenesis can be traced with appropriate vital cell labels and molecular markers. Embryos in culture are also amenable to direct experimental manipulations for elucidating developmental mechanisms of embryogenesis, germ layer formation, and embryonic patterning. This chapter outlines protocols for culturing mouse embryos at the immediate postimplantation period. We also present a system of developmental staging so that the outcome of different embryo culture studies may be assessed properly with reference to the precise developmental stage of the embryos used for the specific experiments.