This article reviews recent studies which have examined various aspects of friendship relations in adolescence. Friendship relations are of central importance in the social life of adolescents because they assume a crucial role in certain developmental functions: emancipation from parental guardianship, commencement of heterosexual relations and affirmation of one's identity. This article reports on various aspects of friendships in adolescence: number of friends, places of recruitment, frequency of meetings, and common themes of conversations. Friendship relations are relatively conflict free in adolescence. They can be characterised by three main elements: trust, communication and intimacy. Friendships evolve in adolescence from a common interest in activities to a sharing of opinions, emotions and feelings. At all ages, girls value the elements of friendship more than boys. In the last ten years research has demonstrated that there is a correlation between adolescent friendship, coping mechanisms, and the acquisition of social skills. The quality of friendship relations and particularly the ability to communicate personal worries predicts this correlation better than the number of friends. The research in the field of friends versus parent influence has abused the concept of peer pressure in committing delinquent crimes. Indeed there is a great deal of agreement between parents and friends in terms of moral values and academic and vocational aspirations. The influence of friends predominates only when there are severe conflicts between parents and their children.