Odontogenesis, is the process of tooth formation, eruption, and integration with its surrounding tissues. Human genetics and mutant animal studies have identified a complex molecular regulatory network that controls tooth development. This book summarizes the complex process of tooth development in which reciprocal and sequential interaction between oral epithelium and mesenchymal cells, which regulates cell activities like cell proliferation, condensation, adhesion, migration, differentiation and secretion which leads to formation of a functional tooth organ.