Following on the work of Kanner, Rank, Geleerd, and Mahler, the author describes in detail the clinical characteristics and dynamics of a group of children with severe ego disturbances of a non-neurotic type characterized by arrested development. Immature object relationship with features of omnipotence and faulty and defective reality testing arising from inadequate defensive structuring are typical. This group represents the pool from which some acute and subacute psychoses and a variety of less dramatic, non-regressive narcissistic disturbances emerge. There is a résumé of the literature connecting this type of child with clinical entities found amongst adult patients, and the writer describes the progress and outcome of treatment in a girl patient whom she followed from her tenth to her eighteenth year.