This chapter discusses the least demanding structural setting that permits no more than unilateral action. In a sense the "anarchic field" describes a nonstructure, or an institution-free context, in which individual actors will interact with one another in the absence of a preexisting relationship, or of specific obligations, between them. In any case, noncooperative games in the sense discussed thus far are not the only mode of interaction that may occur in anarchic fields or in minimal institutions. Property rights and legally binding contracts are also the minimal institutional conditions presupposed by economic theories of market transactions among strangers. Of course a post-outcome analysis must consider not only the original constellation of preferences but also the positive and negative incentives provided by the preexisting institutional framework on the one hand and produced by the interaction in question on the other.