Perceived social support has been widely recognized as having beneficial effects on a person's development, and adolescence is no exception. The objective of this article is to go beyond this "stereotypical" vision of friendship by showing that social support does not always have a positive and direct effect on adolescents' academic achievement. We sought to understand whether this relationship is mediated by the educational goals and motives that student value and pursue. If these values do not coincide with the expectations and values that the academic institution seeks to transmit, the influence of social support can become harmful, especially with regard to the students' academic achievement. Data were collected by means of questionnaires from 676 junior high school students in 9th grade from contrasting academic institutions. We chose to observe each participant's subjective point of view of three dimensions: social support, academic achievement, and educational goals and motives. The results showed that the relationship between "social support" and "attention and involvement" in class was negative and mediated by students' goals. The adolescents with a high level of social support mainly pursued social goals and neglected achievement and future goals. Consequently, these students were less attentive and involved in class. The results also showed that social support was predictive of students' investment and interest in personal work and success, but only when the students pursued achievement and future goals.