This NATO Advanced Research Workshop held 25-30 September, 1988 at the Villa Gualino, Turin, Italy, was the first international meeting of its kind to be devoted solely to cell separation in plants. The partial or complete dissociation of one cell from another is an integral process of differentiation. Partial cell separations are basic physiological components of the overall programme of plant development. Complete cell separations are major events in the ripening of fruits, and the shedding of plant parts. Unscheduled cell separations commonly occur when tissues are subjected to pathogenic invasion. Environmental stresses too, evoke their own separation responses. Over the past five years much new knowledge has been acquired on the regulation of gene expression in specific stages of cell differentiation. Specific molecular markers have been identified that designate the competence of cells for achieving separation. Certain of the chemical signals (hormones, elicitors) that must be emitted or perceived by cells to initiate and sustain separation, are now known to us, and the resulting cell wall changes have come under close chemical scrutiny. The Turin meeting was a focus for those currently involved in such investigations. It assessed factors controlling cell separation in a wide spectrum of different cell types under a variety of conditions.