Type 1 diabetes affects over 1 million persons in the United States, with over 30,000 new cases diagnosed annually. Transplantation of new insulin-producing b cells, in the form of the whole pancreas or isolated islets, has been shown to ameliorate the disease by eliminating the need for exogenous insulin and normalizing glycosylated hemoglobin levels. Islet transplants are a particularly attractive form of therapy because they are a minimally invasive procedure and are more likely to be scaled-up to treat the large numbers of people affected by diabetes. Currently, only a handful of programs have been successful in the endeavor. Nevertheless, the early clinical experience strongly demonstrates that islet transplantation is an effective treatment strategy in select patients with type 1 diabetes. To scale up this therapy and use it earlier in the disease and for more people, the shortage of suitable donor tissue must be solved and the requirement of lifelong immunosuppression must be minimized.