The period of adolescence is a process of maturing and growing up, which each individual endures in their own way. Above all, adolescence is marked by intensive peer connections, since peers become an adolescent’s second family. During this period, young people are faced with new social groups, norms, roles and expectations, all of which have a significant impact on the development of social competence and social identity of young people. They are especially sensitive and susceptible to the influence of their peers and they strongly express their wish to be accepted by their peer group. The growing role of peers in a developing life of an adolescent and his or hers sensibility to their influence will be explained in this review paper. The main focus of this paper is on the influence of peers as one of the main mechanisms of socialization during adolescence. The paper begins with an introduction to the period of adolescence, which is followed by descriptions of peer groups and their meanings and the influence of peers and peer pressure. The paper also examines the concept of family and family relations connected to susceptibility to the influence of peers. Generally, the paper provides an overview of recent research papers dealing with peer relations in adolescence.