Résumé : Understanding the factors that may impact how well universities are transforminga set of inputs into research outputs is of great interest for university andpublic authorities. The goal of this paper is on the one hand to measure the researchefficiencies of US universities and on the other hand to study the impact ofenvironmental variables on them. To reach this objective, the latest techniques innonparametric frontier models are used with both classic and robust methodologies.Focus is in particular devoted to the impact of the institution type (publicor private), the teaching load, the degree of collaboration with industrial partnersand the degree of international collaborations on the production process associatedto research activities. The impact of the size of a university on the way ressourcesare used regarding research activities is also studied.