In the wake of his death, it is a fair tribute to Gilbert Gottlieb to recognize him as a central figure in the creation of conditions that permitted the introduction of developmental thinking in developmental psychology. These included exposing the sterility of the nature-nurture debate and the adoption of a biological framework that conceives of living entities, not as machines, but as self-organizing systems. It is from this vantage point that Gottlieb brought to the attention of psychologists the epigenetic view of development. In this article I summarize various themes that were central to Gottlieb's conception of epigenesis, including, the notions of differentiation and functional integration, bidirectionality between structure and function, and the fact that new information for development is generated by the process of development itself.