Lean Startup is a framework for entrepreneurship that has gained considerable popularity among entrepreneurs, yet the framework has not been thoroughly scrutinized in academic circles. This thesis aims to fill this gap in two ways. First, by comparing Lean Startup to more established models on entrepreneurship in a theoretical perspective. Second, by conducting an empirical study of how Lean Startup influences entrepreneurial success in practice. In our theoretical review, we found that while Lean Startup has a more specific focus than the other theories reviewed, the guidelines it proposes are also present in older theories. In our opinion, the biggest contribution of Lean Startup is making entrepreneurship theory more accessible to entrepreneurs. The empirical study was conducted using a quantitative research design, and corroborated the findings from the theoretical review: There was no significant correlation between use of Lean Startup and the likelihood of achieving success.