This article aims to present the activity as an interface amongst different actors in a project process. As based on the ergonomic intervention in a university restaurant, the kitchen assistants’ activity at the meal serving counter is presented as an interface among nutritionists, managers and operators of this food supply system. Building this interface in the re-evaluation meetings of this project aimed to support the dialog amongst heterogeneous actors, thus allowing for the transformation of this system and the improvement of the work conditions for the kitchen assistants.