During embryogenesis, the vascular network is formed by two distinct mechanisms, vasculogenesis and angiogenesis. Vasculogenesis refers to in situ differentiation and growth of blood vessels derived from hemangioblasts or endothelial precursor cells, while angiogenesis is involved in the expansion of the vascular network. Angiogenesis occurs during both embryonic and adult life, but vasculogenesis was considered only to be present in the embryo. This paradigm came under attack when endothelial progenitor cells where found circulating in adult blood vessels. Today, there is no consensus about the importance of vasculogenesis during postnatal life despite increasing evidence. Another aspect is the notion of arteriogenesis which is closely linked to postnatal vasculogenesis (PNV). In this chapter, we will not only discuss the cellular origin and mechanistical aspects but also describe strategies that are developed to induce PNV which may be therapeutically relevant. Moreover, we will explore tissue-engineering technologies which may be considered as a kind of artificial PNV and which represent promising tools for vascular and tissue repair in adults.