Institutional Economics, especially the Principal-Agent Approach and Transaction Cost Economics, has proven of value in various disciplines (e.g. marketing, personnel management). However, so far they have hardly expanded into entrepreneurship research. In this paper, we strive to analyse the establishment of new ventures from the perspective of Institutional Economics. This highlights the decisive role of the relationship between the founder and the stakeholders. The success of a new venture strongly depends on the acceptance and the support of the stakeholders. At the same time, the relationships to the stakeholders are burdened with particularly high uncertainties, because of the “liability of newness.” When evaluating the offered transaction, the stakeholder is confronted by the founder’s insecure promises. These insecurities influence the potential stakeholders’ decision whether or not to establish a transaction relationship with the newly founded company. With the rising capability to handle such insecurities, the success of the new venture becomes more likely. As a pragmatic-normative tool to structure and handle the insecurities identified, the MUT-Approach presented in this paper can foster the success of new ventures by helping the founder to establish stable relationships with stakeholders.