past, but we are unwilling, at present, to claim that the reverse is true. Second, and far more intriguing, is the increasing importance of what sociologists call the horizontal division of labor. By a horizontal division of labor, sociologists tend to mean an occupational division of labor in which expertise is distributed among groups of specialists. In a vertical division of labor, expertise is lodged in organizations and structured in series of proper subsets that form an inclusion tree or a hierarchy in which superiors know what subordinates know and more. The tendency toward the reduction of job categories and the increasing scope of work in blue-collar work, the expansion and proliferation of professional and technical jobs, the segmentation of service work by problem area and market, and the hypothesis of increasing specialization of managerial work all point to a more horizontal system for organizing tasks, skills, knowledge, and responsibility. In horizontal divisions of labor, coordination occurs though the ongoing collaboration of experts rather than through a system of command and control. Should the general nature of work change to favor a more horizontal division of labor, it would represent a reversal of one of the primary attributes of the industrial era: the primacy of bureaucracy and hierarchy. In an economy marked by a horizontal division of labor, content and knowledge would become more important than command and control as vectors for organizing.