The qualitative descriptive study whose objective characterizes the self-concept of two boys and two girls, trying also to identify differences and similarities between them with those who fail in school and those who succeed in school. To accomplish this, it goes back to the case study method, which allows for a more profound comprehension of self-concept in the two boys and the two girls, who are in the third grade at El Centro Educativo Fe and Alegria Patio Bonito. The instruments that were used to come to such a conclusion were, the questionnaire of self-concept by Piers-Harris, The way I feel about myself , structured interviews applied to professors, semi-structured interviews carried out by the girls and boys and the participant observation inside and outside of the classroom. The information obtained was analyzed in light of five categories constructed previously that are based on the questionnaire by Piers Harris, in which they were enriched with the actual data and the theoretical framework. The results permitted us to characterize the self-concept of each one of the cases and perform a comparative study between the boys and girls who fail in school and those who succeed in school.