Over the last decades, European cities have been facing serious constraints. In particular, decreasing transfers from central governments, the introduction of domestic 'Stability pacts' and the economic crisis have significantly challenged the capacity of local governments to address societal issues. Within this context, local governments have tried to find new ways by establishing collaborations with a wide range of private actors, including nonprofit organizations and the civil society as a whole. Among these private actors, big philanthropic organizations are gaining prominence, acting as public policy supporters and policy makers. In particular, those philanthropic organizations, which focus the operating activity on single communities, are emerging as potential key actors in local governance, thanks to their capacity to concentrate resourses and efforts in specific and limited territories. For this new emerging role, a recent debate on their impact on local policy making has raised in the last years. This paper aims at presenting the findings of a comparative analysis on the impact that some of the world's biggest philanthropic organizations have produced in two Italian urban contexts. In particular, the comparative analysis of these two cases had the aim of testing a major thesis: the impact of philanthropic foundations on local policy making varies in relation to the consolidated mode of governance within which they operate.