How is the process of differentiation regulated? What are the signals which cause a cell or a group of cells to change their mode of growth? Studies in this area are amongst the most challenging in modern biology. While outstanding progress has been made in the study of differentiation in mammalian, including human, systems, development can very profitably be investigated in simpler organisms due to the ease of manipulation of their life cycles and genetics. Three major areas of knowledge must be obtained in studies of differentiating systems: the nature of the cell before the differentiation process begins, including structural and physiological information; equivalent data on the differentiated cell type; and lastly, an understanding of the mechanisms involved in the transition between the two cell types. To further these studies, the International Spores Conference, Inc. was created to sponsor international symposia in the area of prokaryotic development, with special emphasis on sporulation. The 10th International Spores Conference will be held at the Marine Biological Laboratories, Woods Hole, Massachusetts, from March 23 through March 27, 1988. The Conference will bring scientists from all over the world, both from academic and industrial laboratories, who are interested in prokaryotic development and differentiation. The primary emphasis of the Conference will be on bacterial sporulation, but at least one session will be devoted to problems of development and global regulation in other microorganisms. The Conference will focus on the regulation of gene expression during sporulation, including the initiation of the process, the physiology of spore germination, structural and functional studies of spores, including mechanisms of spore resistance, and one session will deal with sporulation related products of industrial importance, including insecticides and exoenzymes. The formal program of nine sessions will be supplemented by poster sessions and informal round table discussions on specific topics.