The most visible elements of workforce inequality are who gets hired, how much they get paid, and whether they get promoted. Matching, incentive, and mobility are connected processes. In bundling certain work contracts together, employers and workers simultaneously link jobs and value them relative to each other. In firms, gross person-to-job matching occurs chiefly through hiring, contracting, promotion, separation, and transfers, whereas fine matching takes the form of day-to-day modification in a jobholder’s work contracts. A man acquired the job either by moving up from helper or by the foreman’s hiring him from outside. In a nineteenth-century cotton mill, for example, “mule spinner” designated a job with well-defined, crucial responsibilities: work contracts tying the position to other workers, to helpers, and to foremen. Labor market organization and social segregation are logically separate processes, but the maneuvers of employers and workers often make them coincide.