This paper summarizes my thesis prepared and examined at the IREDU – Université de Bourgogne. This work is a reflection on a crucial problem of university failure in academic first cycle, particularly in first year. It deals with the effectiveness of the “SPESS” (Preparation Semester for Higher Scientific Studies instituted in order to help weak students). Based on the theoretical development of estimation of the school acquisitions production function, and on the costeffectiveness studies, the empirical part of this work concentrates on the linear and the logistical models associated respectively to the explanation of the different forms of success : different scores out of 20 and chances to pass in the higher level. The results indicate the impressing negative effect of the “SPESS”.