A methodical policy intervention in road safety was designed and implemented in Chile starting in 1993, which turned out very successful. It changed dramatically a growing trend in traffic deaths and reduced deaths per 100,000 population from 13 to 10 in less than 10 years. The overall cost has been around US$ 20 million. The intervention's methodology was the Participatory Innovation Model (PI Model), an approach to action in complex systems developed by the present author, who was the methodological consultant in this case. This paper is intended to put forward the PI Model as a practical option for facing the road safety crisis in the lower- income world. For this purpose it presents the conceptual grounds on which it is based, it briefly describes the Model's management principles, concepts and tools, and it shows the concrete results of the application in Chile. The paper closes by outlining a program for transferring the Model to interested countries or international agencies. Some key aspects of the paper should be highlighted: (1) it distinguishes between two key components in any road safety policy, i.e., the technical measures and the systemic foundations, and shows that the PI Model deals with both; (2) it places road-safety policy making among "high-complexity" action problems, because of the great number and diversity of relevant issues, actors, disciplines and cultures it involves; (3) it presents the conditions for effectively facing this class of problems, which are established by an important law of systems; (4) it compares, on the basis of this law, the likely effectiveness of several approaches to road-safety policy intervention, including the PI Model; and (5) it describes the following outputs of the Chilean intervention; a critical mass of committed and mobilized road-safety actors, a powerful vision of development, the creation of a sustainable lead agency (i.e. CONASET), the effective implementation of a large number of projects, the impact on lives saved and on people saved from being injured, the low overall intervention cost, and the estimated overall economic impact of the policy, i.e., saving US$ 10 billion.