Since 2002 the German government has promoted private retirement saving plans by means of special subsidies and tax incentives (Riester scheme). This policy mainly targets low-income households. Using data from the German Socio-economic Panel, we scrutinize the impact of the Riester scheme on private savings. Our empirical strategy consists of treating the introduction of the Riester scheme as a natural experiment. The estimation results cast some doubts on the effectiveness of the Riester scheme in raising private savings and call for enhanced systematic efforts to evaluate that policy.