: This article provides a first empirical study of the determinants of the interdisciplinarity of academic researchers production. For that purpose we measure interdisciplinarity as the diversity of their research production across scientific domains. Our evidence is based on more than nine hundred permanent researchers employed by a large French university which is ranked first among French universities in terms of Impact. Our main results are that the traditional academic career incentives do not stimulate interdisciplinary research while having connections with industry does. The context of work in the laboratory strongly affects the propensity to undertake interdisciplinary research. Key words : Economics of science, Academic incentives, Interdisciplinary research, Laboratory, University. JEL classification : L31, 031, 032, 034, 038. * Corresponding author. BETA, PEGE-ULP, 61, avenue de la Forêt Noire, F-67085, Strasbourg Cedex ; tel : +33-390242104 ; fax : +33-390242071 ; email : .φ This work is part of a larger project on knowledge production at ULP. We are grateful to P. Llerena, M. Matt, S. Wolff and all other members of the team. L. Bach's comments helped us to improve the paper. Acknowledgements extend to the administrative departments and the Technology Transfer Office at ULP, and to the CNRS Industrial Liaison Office.