Since the call to take the analytical and theoretical values of historical institutionalism seriously, planning history research has emphasized the enduring legacies of critical moments that structure the developmental pathways of urban institutions, whose changes tend to appear incremental in the long run. Yet, most of this work is less conscious about deliberate – although not always successful – considerations by policy actors in formulating policies and conflates changes in institutional arrangements with changes in policy effects. This article fills these gaps from a policy design perspective, explaining the changing policy effects of the same institutional arrangements over time through design processes such as layering. To this end, it introduces Vienna's participatory urban renewal model, Soft Urban Renewal, highlighting its context-bound design space in which policy actors choose and rearrange existing instruments according to shifting policy objectives and circumstances. Two cases of Soft Urban Renewal from two different points in time are chosen to cross-compare their varying capacities to influence its real-world effect under different contextual constraints. It concludes with some final remarks on the ways in which a policy design perspective can contribute to the current debate on planning history research and comparative-historical analysis of cities and their institutions and policies.