While tests of producer rationality defined as conformity to the rules of profit maximization (or a similar postulate) for less developed countries are numerous, such tests for high-income countries are rare. This study investigates the extent of rationality observed in the production behavior of ranchers in southeastern Montana. The procedure used is that of Wise, Yotopoulos, and Nugent, based on a profit-maximizing production model. The data were collected by personal interviews for 69 ranchers. Results indicate that profit maximization is a reasonably good postulate for studying the behavior of ranchers, and that various policy measures, could, at least tentatively, proceed on that basis.