In both plants and animals, embryogenesis is the beginning of a new life, during which the basic body pattern is established. In flowering plants, embryogenesis starts with a single-celled diploid zygote, formed by the fusion of an egg and a sperm cell within the embryo sac during double fertilization. Another sperm cell carried along by the pollen tube fuses with the diploid central cell in the embryo sac to produce a triploid endosperm that nourishes the embryo during embryogenesis and, sometimes, seed germination as well. In embryo development, cell divisions and cell fate specifications occur orderly to produce elaborated architectural patterns of tissues and organs for a mature embryo. In this chapter, we give a general overview of key developmental events in plant embryogenesis, including polarity setup, zygote activation, tissue pattern formation, and organ primordial establishment, with attention to molecular mechanisms underlying these processes known to date.