This chapter studies the labor managed firm using a short run framework where capital is fixed. A long theoretical tradition based on the work of Ward, Domar, and Vanek argues that LMFs maximize income per worker. The chapter criticizes the WDV model and contrasts it with a model developed by Sertel and Dow where LMFs with competitive membership markets maximize profit. This contrast is developed first in an elementary setting with a single firm. The analysis is then generalized to an economy with many firms but only one consumption good. A 'Sertel-Dow' equilibrium is defined for this economy. Such an equilibrium exists and is isomorphic to a Walrasian equilibrium. The chapter closes with an assessment of the WDV and SD models based on criteria of ex ante and ex post workers' control. One key weakness of the WDV model involves its failure to connect the maximization of income per worker with the goals of individual agents. By contrast, the SD model derives the maximization of profit from the interests of the subset of workers holding ex ante control rights within the firm.