Lonely children are often 'unpopular' children, meaning children who are not readily accepted by their peers and who do not make friends. Children may be isolated or rejected because they are unaware of the modes of behaviour which contribute to peer acceptance, they lack insight into the adverse effects of their behaviour on peer relations and they lack the social skills necessary for making friends. The lonely child lacks a feeling of security and belonging.
Major categories of isolated children are those with impairments; those who are new in a community; those whose parents are excessively conspicuous due to position, behaviour, history or unusual circumstances; those in linguistic, racial, ethnic or religious minorities; and children who are categorized, less scientifically, as introverted, intellectual or awkward. In the developmental cycle, the onset of puberty may create behavioural and psychological manifestations leading to separation from former friends. The adolescent may be the individual who feels loneliness most keenly. In some cases this may lead to leaving home prematurely under conditions as varied as premature marriage, military enlistment or running away.