This paper develops the basis for a decisional organization theory. Important approaches, like sociological systems theory, partial and meta-organization or organizationality, share the assumption that decisions are a central component of organizations. However, organization studies still fail to fully account for the role of decision in the emergence and continuation of organization. Yet, while pre-modern societies could rely on institutionalized orders in the form of traditions and authorities, the contemporary world rests on a myriad of decisions to cope with societal complexities. We develop an integrated, decisional organization theory (decisional OT) in which we articulate several concepts of organization theory, thus presenting organization as both a system of decision and a decided social order. Further looking at organization as a continuum, we distinguish between 'entitative organizationality', i.e., degrees of organizationality at the entity level, and 'structural organizationality', i.e., combination of organizational elements. This approach constitutes an important development for OT because it helps us analyze the complex layering and intertwining of social orders inside, outside, among, and as organization(s), and identifying future research on the nesting of organization and the maintenance of organizational boundaries.