Wolfgang Streeck convincingly argues, in an influential paper published in 1997, that economic performance in market societies is enhanced when the rational, voluntaristic choices of actors are constrained by a variety of normative and institutional constraints. This paper offers three modifications of this central Durkheimian thesis: (1) the meaning of good performance of an economic system differs among class actors in a market economy; (2) the level of institutional constraint that is optimal for good economic performance in the interests of capitalists is generally lower than the level of constraints that is optimal for workers; and (3) institutional constraints on voluntary rational choice - even those optimal for capitalists - also may have dynamic effects on the balance of power among social forces which could lead capitalists to prefer suboptimal constraints from the point of view of economic performance.