A startup’s business model reflects how the founders intend to generate revenues and why they believe that this will be a success. Publications in the domain of Lean Startup (e.g., Ries, 2011; Blank and Dorf, 2012) urge nascent entrepreneurs to specify the assumptions behind their business models and to validate these in a fast-paced process with limited investments. In addition, this approach urges nascent entrepreneurs to develop and refine their business models by means of interaction with prospective users. Although this relatively young approach draws heavily on well- established academic insights – most notably discovery-driven planning and real options theory (McGrath and MacMillan, 1995) – there is a strong need for a better empirical understanding of the startup business modeling process, its determinants, and its impact.