ABSTRACT
Knowledge of what is normal plays an important part in determining what is abnormal. Therefore, the normal development of children is a fundamental issue in relation to mental health disorders that have been traditionally described in terms of deviations from normal development and behaviour. Whilst the boundary between what is normal and what is abnormal is not distinct, it is important to define as clearly as possible what is normal or age-appropriate behaviour, even though this is necessarily somewhat arbitrary. When considering mental health problems in children and adolescents it is therefore essential to have an understanding of normal child development and the processes involved. Many behaviours are normal at certain ages, but not at others. Also, many mental health problems in childhood and adolescence may be manifestations of disturbed development. Childhood and adolescence are particularly dynamic periods of development involving many changes. These include cognitive, emotional, social, sexual, as well as biological changes. During this period children are transformed from helpless, dependent infants to independent, self-sufficient individuals with their own views. This is, of course, a complex process with much continuity and some discontinuities.
