This monograph contains papers which resulted from an international workshop on the effects of lithium on the hematopoietic and immunologic systems. The meeting was held at the John L. and Beatrice Keeshin International Biomedical Systems Planning Center of Rush University in Eagle River, Wisconsin from June 6 through June 9, 1979. The object of this conference was to bring together scientists from around the world with an interest in the effects of lithium and its potential use in human disease to bolster and stimulate the hematologic and immune systems. These topics seemed to us to be important and the time seemed right for bringing together the workers in these fields to exchange ideas and recent research results. We sought to bring together basic research scientists trying to uncover the mechanism of action of lithium in the stimulation of granulopoiesis and in its immunologic effects, together with those involved in clinical care and the use of lithium as a therapeutic tool in neoplastic and non-neoplastic disorders. This was the first use of the Keeshin Center for such a program. The sessions were conducted in a relaxed atmosphere with a good deal of give-and-take by all the participants. The editors of this book hope that it will be useful as the first volume completely devoted to these applications of lithium in these new and, as yet, incompletely developed fields.