We use three complementary quasi-experimental approaches to study the causal effect of introducing a penalty-point system (PPS) in Spain in July 1 2006, on drivers' behavior. According to Regression-Discontinuity (RD) estimates, the PPS decreased the number of traffic offenders by 14%, and this deterrence effect was directly related to the severity of the penalty. Concerns that RD estimates may over-or under-state the longer-run effects of the policy change are addressed by presenting the Difference-in-Differences (DiD) estimates, which reveal that the deterrence effect of this reform increased over time. Crucially, the reform also curbed accidents by 14%, injuries by 16%, and fatalities by 14%, and these effects persisted over time. Difference-in-RD estimates are consistent with the other two approaches. Altogether, the reform represented net benefits of over 946 million EUR per year (or 0.09% of the Spanish GDP) during the first three years after implementation. (c) 2021 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )