School Adjustment is considered to be an outstanding factor in order to understand and give a pshycoeducational response to the growing problems of academic failure, truancy and cohabitation in the classroom. Self-concept has likewise an essential role in students' adjustment. The aims of this study are to analyse the relationship among Academic and Global dimensions of Self-concept and School Adjustment's scales; to examine the differences in School Adjustment, as well as in Academic and Global Self-concept, according to the students' gender and age; and to check predictive ability of Academic and Global Self-concept on School Adjustment. 1468 students participated in this studybetween 11 and 17 years of age(M=14.03; SD=1.36), 51% women and 49% men. The Brief Scale of School Adjustment (EBAE) and the Multidimensional Self-Concept Questionnaire (AUDIM) were implemented. The School Adjustment keeps significant relationships with the Self-concept. Furthermore, women have been considered to have a larger School Adjustment and Academic Self-concept in oral skills, while men perceive better the Mathematic and Global Self-concept. Besides, the Self-concept and the School Adjustment are larger in the early adolescence than in the middle adolescence. Finally, the Academic and Global Self-concept have a high and moderate predictive ability about the School Adjustment's dimensions, and the Academic Self-concept a remarkable influence regarding the academic achievement.