Book excerpt: A model of endogenous payoff motives and endogenous order of moves is analysed in a mixed duopoly. We find that, when a non-negative price constraint is imposed on public and private firms' quantity choice, both firms always choose to be relative-payoff-maximisers, and both simultaneous move and sequential move can be sustained in equilibrium. In contrast, when non-negative absolute profit constraint is imposed, public and private firms always choose to be absolute-payoff-maximisers, and only sequential move can be sustained in equilibrium.