Developmental theories are a group of ideas, hypotheses, and generalizations that interpret and illuminate the thousands of observations that have been made about human growth. In this way, development theories provide a framework for explaining development patterns and issues (Berger, 2008 p33). Adolescence represents one of the most critical developmental periods in life. It is a time of profound change at all levels. The importance of family and peers during these years is also discussed. The relationship between the adolescent and his or her family is very important in the adolescent's ability to develop during these years. One of the first theorists to shed light on adolescent development was Erik Erikson. He developed a psychosocial model of developmental stages that applies from early childhood to retirement. Erikson spent a lot of time on the fifth stage of adolescence because it is the time when the individual develops an identity and it is a time when the individual faces difficult identity crises. Erikson explained that each stage of life is both “psycho” and “social.” The psycho part has to do with the foundations of this stage, the previous stages and the fact that it is both a conscious and an unconscious phase. This stage of development therefore depends to a certain extent on psychobiological factors which lead the individual to a coherent perception of himself. The past gives the adolescent the strong identifications made during childhood but at the same time, the individual searches in the present for new models on which to base his adult life (Erikson, 1975). During this time, adolescents must cope with changes in their bodies and conform to higher social expectations from adults and their superiors. Adolescents...... middle of paper...... (1994). Childhood and adolescent depression: covariation and comorbidity in development. in Haggerty, RJ, Garmezy, N., Rutter, M. and Sherrod, L. (eds.). 1994. Risk and resilience in children: developmental approaches. New York: Cambridge University Press, p. 225-67. Erikson, E. H. (1975). Life story and historical moment. New York: Norton. Rutter, M. (1986). The developmental psychopathology of depression: issues and perspectives. In Rutter, M., Izard, CE and Read, PB (eds.). Depression in Youth: Developmental and Clinical Perspectives, New York: Guilford, pp. 3-30.http://social.jrank.org/pages/16/Adolescence.html">Adolescence - Major theories of adolescent development, biological changeshttp://social.jrank.org/pages/15/Adolescence -Biological-Changes-Associated-with-Puberty.html">Adolescence - Biological changes associated with puberty