While a growing body of literature finds positive impacts of Start-Up Subsidies (SUS) on labor market outcomes of participants, little is known about how the design of these programs shapes their effectiveness and hence how to improve policy. As experimental variation in program design is unavailable, we exploit the 2011 reform of the current German SUS program for the unemployed which strengthened case-workers' discretionary power, increased entry requirements and reduced monetary support. We estimate the impact of the reform on the program's effectiveness using samples of participants and non-participants from before and after the reform.