In Europe, the food safety policy combines the regulatory interventions of member states with private standards. The Hygiene Package, which came into force on the 1 January 2006, is characteristic of this model. The aim of our article is to show that whilst we can learn about co-regulation by examining the standards and principles on which it is based, we will gain an even better understanding by examining its actual implementation. From a sociological standpoint, we look at how the Hygiene Package was received and implemented in French slaughterhouses. (1) After setting out the structure of slaughterhouses in France and the ways in which veterinary services are organised, (2) the article looks at how inspection services have been affected by the introduction of the Hygiene Package, particularly with regard to the changes in relationships within the inspection service, between veterinarians and official auxiliaries and (3) it then examines the evolution in roles and responsibilities between veterinary services and food business operators.