The aim of this work is to establish a connection between New Institutional Economics, Neo-Institutionalism, and organizational consulting. First, the term "organizational consulting" is briefly defined. Then, the institutional economic theories are presented, specifically the theory of property rights, agency theory, and the transaction cost theory of organizations, as well as the neo-institutionalist approaches in organizational theory. Here, a distinction is made between macro- and micro-institutionalist approaches. A brief excursion introduces the reader to the topic of power, as this aspect plays an important role in the present discussion. Finally, the influences of New Institutional Economics and Neo-Institutionalism on the consulting industry are highlighted, which are reflected in selection processes, contract designs, and incentive systems on one hand, and appear in trends and methods on the other.