In 2014, France hosted the World Equestrian Games in Normandy. As part of a collaborative research program carried out by IFCE (French Institute for Horse and Riding), INRA (National Institute of Agronomic Research), and Limoges CDES (Sports Economics and Law Centre), an impact study of the event and its associated Territorial Project was conducted. This is one of the few studies, which measures the economic, social and environmental impacts of an event of this scale. These three approaches are complementary, appreciating changes in the level of economic activity, people’s well-being, and state of the environment. To this aim, a methodology has gradually been built and tested during previous years on various small size equestrian sporting events. It combines quantitative and qualitative approaches, pushing the classical limits of impact studies. The economic evaluation uses Base Theory and Keynesian multipliers. Social utility is addressed through the monetarization of use and non-use values of the event for spectators and inhabitants (thanks to the travel cost method and the contingent valuation method). This quantitative evaluation is completed by a qualitative analysis to describe the reasons why people give use and non-use values to this event. We studied the various items that affect the environment through their specific units and through an analysis of the organizers’ efforts to minimize the impact of the event. We based the results on the collection of information from the Games organizers, field observations and around 2,300 surveys conducted during the event. The Alltech FEI World Equestrian Games™ 2014 in Normandy brought together 313,556 spectators and 1,060 participants. Their total economic impact amounts to 102 million euros for Normandy while the operating budget of the event was €82 million (including €40 million of public money). From a social point of view, the contributions of this event are mainly related to the pleasure of attending it or of hosing it and to its public good characteristics: economic and tourist benefits, media exposure, attractiveness of the local area, and encouragement of the development of the local and even national equine industry. The social utility of the 2014 WEG is estimated at 45 million euros. On the environmental aspect, our analysis highlights the numerous efforts of the organizers to aim towards the organization of an eco-responsible event. This study represents both a contribution to academic research and to the horse industry, participating in the methodological and theoretical advances in impact studies and in reflections on optimizing the benefits of equestrian events for the territories that host them.