Sine et al. (2006) state that start-ups generally perform best when they have a relatively high degree of structure. Others defend the notion that entrepreneurial firms benefit most from being organically organized (Burns & Stalker, 1961). In resolving this dilemma between mechanistic or organic structures, one should rather focus on the way they are dealt with. In order to boost performance, a start-up, albeit structured (Stinchombe, 1965), has got to be managed in a strategic flexible way (Covin & Slevin, 1989). As the direction of a new venture is highly influenced by the skills and objectives of its founder (Bruderl, Preisenddrfer, and Ziegler, 1992), the aim of this study is to unravel the profile of a successful founder in terms of his adaptability: Does having a low conscientious personality combined with a highly flexible mindset optimize decision-making performance in venturing context?