Contention is a particular collective form of bargaining. Contention joins three elements: claim-making and strategic interaction involving the deployment of commitment, coercion, and compensation as incentives for supporters, allies, rivals, and objects of claims. Far from being an epiphenomenon of more basic economic changes, furthermore, contention over work makes a difference to the organization of production. Collective contention fully involving ordinary workers occur more rarely and entail social processes that do not happen every day. Given great asymmetries of power and organization between capitalists and workers, indeed, large-scale worker-initiated contention poses difficult explanatory problems. All performances that characterize claim-making among a specified set of collective actors constitute that set’s repertoire of contention. National politics set important limits within which changing conditions of work generated contention. As with technological invention, innovation in contention follows strongly path-dependent trajectories, referring repeatedly to accumulated, reinterpreted experiences in past and present.