Angiogenesis is the process of neovascularization from preexisting blood vessels, whereas vasculogenesis is the process of blood vessel generation from angioblast precursor cells. The human placenta undergoes high levels of angiogenesis and vasculogenesis during fetal development. Additionally, the placenta undergoes a process of vascular mimicry (also referred to as pseudovasculogenesis ) in which the placental cytotrophoblasts convert from an epithelial to an endothelial phenotype during normal fetal development. Failure of placental angiogenesis and pseudovasculogenesis during placental development has been linked to the pathogenesis of preeclampsia. It currently is believed that soluble factors released by the diseased placenta lead to clinical findings of preeclampsia. This article discusses placental vascular development in health and in disease, with a focus on accumulating recent evidence that the maternal clinical syndrome of preeclampsia is an antiangiogenic state resulting from an excess of anti-endothelial factors liberated by the diseased placenta.