Indifference curve analysis, a favorite indoor sport of economists, has proven itself to be invaluable in the exposition and development of many branches of economic theory. One can scarcely imagine, for example, analyses of consumer behavior, welfare, or international trade which did not at some stage employ indifference curves. On the other hand, this apparatus is used infrequently in the theory of the firm. Pricing and quantity decisions of the firm in both its output and factor markets, and decisions on firm size are usually analyzed in marginal terms, money or real, without recourse to indifference analysis.' The reason for this apparent neglect is not hard to find. For indifference analysis to be fruitful, utility must be derivable from two or more sources. We assume, however, in dealing with the firm that the utility derived by the entrepreneur from the operation of the firm is a monotonically increasing function of profit alone. By maximizing his profit, the entrepreneur automatically maximizes his utility. Economists have usually been willing and even anxious to modify conclusions based on profitmaximizing models whenever circumstances have suggested that non-pecuniary motives were important. It is only recently, however, that attempts have been made to modify the models themselves by recognizing in their construction some non-profit-maximizing motivations.2 If the entrepreneur derives utility from some source o her than profit, the groundwork is laid for the fruitful application of the indifference technique. My rather modest intentions in this paper can be summarized as follows: (1) to depict the profit maximization principle in a way which has certain pedagogic advantages over the usual resentation and which may reflect more accurately the profit maximizing procedures used by management, who, it is claimed, does not compute marginal revenue and marginal cost; (2) to mod fy the profit maximizing model for the possibility that the entrepreneur derives utility from some variable which is a monotonically increasing (or decreasing) function of quantity, total revenue, or size; and (3) to show how some of our usual conclusions about the behavior of