Patients suffering from type 1 and type 2 diabetes exhibit a decrease in the mass of insulin-producing beta cells. Both the ability to generate and expand large amounts of transplantable beta cells and the capacity to encourage beta-cell proliferation in the patient represent potential cures for the disease. Understanding the basic cell cycle machinery responsible for the replication of pancreatic beta cells is therefore an important challenge in diabetes research today, in hopes that it will provide useful insights into betacell growth and proliferation. Though for many years pancreas biologists believed that adult beta cells emerged from progenitor cells and remained post-mitotic throughout their lifetimes, recent work has demonstrated that adult beta cells are a dynamic and replicating population. In light of this new understanding of pancreatic beta cells, much attention is currently being focused on the regulation of the replication process. However, even as biologists focus on the particular machinery involved in division, a proper understanding can only be obtained in light of beta-cell development, origins, and dynamics. In this review, we present a brief introduction to beta-cell development and origins, followed by a description of beta-cell proliferation machinery. We conclude with a discussion of a possible regulatory model for beta-cell proliferation.