This paper shows a general overview regarding Spanish students performance in Math, in Compulsory Secondary Education. Some variables related to student and school background information have been selected in order to identify their relation with Maths’ achievement. So that, using database from PISA 2003, a multilevel analysis has been undertaken in order to explain the existing variance among students and among educational centres, and, in this way, to develop an explicative model of the Spanish students performance in Math.