The main purpose of this work was to build a model to evaluate the family farmers’ supplies to the restaurant of the Federal University of Pelotas in Southern Brazil. A Constructivist Multicriteria Methodology for Decision Aid (MCDA-C) was used and helped to identify, organize, measure and aggregate all criteria which will be useful to compare all suppliers to the best interests of the University restaurant. This research can be described as a study case both a qualitative and quantitative approach which used an interview technique (cognitive mapping) to gather data to build the model. The main results indicate that the standard supplies, price within market range, compliance to delivery volume standards, on-time delivery and farmers’ storage capacity are the key evaluation criteria. In addition, the structuration process allowed: a) a better understanding for the restaurant manager of the farmer’s profile most suitable to the restaurant operations; and b) a way to communicate which criteria will be used to evaluate them.