A workshop sponsored by the National Institute of Child Health and Human Development was held in June 1988 to discuss the initial events in the pathogenesis of insulin-dependent diabetes and to make recommendations for future studies. Better definition of immunological markers to reliably predict the disease will enable the detection and study of the earliest pathogenic events involved. The precise autoimmune mechanisms and the role of the environment, both in the initiation of the disease process and precipitation of clinically overt disease, need to be accurately determined to define strategies that might eventually lead to its prevention.