Our paper explores in a large Romanian sample (2168 adolescents) the relational costs and benefits of the number of friends at school. Using the MEDCURVE procedure to test the non-linear mediation effects, our results show that psychological safety, bullying and negative relations mediate the association between the number of friends and depression and anxiety, while social acceptance and bullying mediate the association between the number of friends and academic self-efficacy. In general, our results show that the relational benefits of friendship tend to diminish as the number of friends increase, in general over 9 friends (depending on the relational state) and parents, teachers and school counselors should help adolescents manage their number of friends in order to prevent the relational costs associated with engaging in too many (superficial) friendships.