Peers are one of the key agents of socialization in a child's life. For children and particularly adolescents, peers often constitute their main reference group. In other words, children and adolescents generally compare themselves, what they have, and how they behave to their age mates. In fact, adolescents often guide their own behavior and make decisions based on what their peers say and on their perceptions of what their peers think. This process of orientation toward peers grows in importance with age. It peaks in early and middle adolescence, which is one of the reasons why this period in a youth's life is often difficult, and also why delinquency rates are higher during that time. Then, toward the late teens and for others in young adulthood, age mates recede in importance as the young person is placed in social situations that cut across age groups. Furthermore, by that time, individuals' self-concept is more stable and peer influence becomes less salient as new adult roles are assumed.