There are several positive aspects of peer groups during adolescence. Peer groups can positively affect one's development, and social skills such as empathy, teamwork, leadership, and sharing. Peer groups can have a positive influence on one's life as well, whereas friends can have a positive effect on behaviors, academic performance, and motivation. In Erikson's psychosocial stage model of development, the teenage years stage describes the psychological issues of adolescence. The developmental task is identity versus identity confusion. Whereas adolescents develop a stable sense of who they are and a stable set of values and ideals (Kowalski & Westen, 2011). In this stage one's identity refers to a stable sense of who one is and what one’s values and ideals are (Kowalski & Westen, 2011). Identity confusion refers to a condition in which the individual fails to develop a coherent and enduring sense of self and has difficulty committing to roles, values, people, and occupational choices in his or her life (Kowalski & Westen, 2011). In my opinion teenage years is the most important stage in Erikson's psychosocial stage model of development. In this stage one use decision-making along with the interactions of peer groups to determine who they are, values, and identity.
Kowalski, R., & Westen, D. (2011). Psychology (6th ed.). Hoboken, NJ: Wiley.