Over the last decade it has become clear that many aspects of cell behavior are influenced by cell-cell interactions. Much progress has been made elucidating the signaling pathways downstream from cell adhesion molecules (CAMs). This started with integrins, but more recently, other CAMs involved in cell-cell interactions, including cadherins, selectins and immunoglobulin-superfamily proteins have also been found to initiate signaling pathways. Signaling downstream from cell-cell interactions seems to be particularly important in the development of the nervous system, in the events of inflammation, and in the context of the organization of polarized epithelia. Whereas normal cell-cell interactions are important for normal growth and differentiation, altered cell-cell adhesion contributes to the development of invasive tumors. ? ? This proposed Keystone Symposium will provide a multidisciplinary approach to key aspects for the emerging research field of CAMs and their role in signaling pathways that affect mitogenesis, cell survival, and cell differentiation. It will focus on several exciting nascent themes including the role of polarity genes, the intersection between adhesion, trafficking, and signaling, and the role of cytoskeletal scaffolds in signal transduction. Leading investigators from around the world working on adhesion molecules, polarity, cytoskeleton, and signaling have been invited to present their findings. The invited speakers include a substantial proportion of outstanding women scientists. A variety of experimental systems and multiple approaches, ranging from structural, to cell biological, to physiological will be discussed. This symposium will also emphasize novel work from young investigators, with several """"""""slots"""""""" in the program reserved for this purpose. The proposed program will present a unique training opportunity for students and post-doctoral fellows, since it will provide a unifying thematic structure to converging, but still disparate, areas of research.