The lack or dysfunction of insulin-producing beta-cells is the cause of all forms of diabetes. In vitro generation of beta-cells from pluripotent stem cells for cell-replacement therapy or triggering endogenous mechanisms of beta-cell repair have great potential in the field of regenerative medicine. Both approaches rely on a thorough understanding of beta-cell development and homeostasis. Here, we briefly summarize the current knowledge of beta-cell differentiation during pancreas development in the mouse. Furthermore, we describe how this knowledge is translated to instruct differentiation of both mouse and human pluripotent stem cells towards the beta-cell lineage. Finally, we shortly summarize the current efforts to identify stem or progenitor cells in the adult pancreatic organ and to harness the endogenous regenerative potential. Understanding development and regeneration of beta-cells already led to identification of molecular targets for therapy and informed on pathomechanisms of diabetes. In the future might lead to beta-cell repair and replacement therapies.