There are few published data concerning the clinical criteria that determine admission of children or adolescents to psychiatric in-patient units. This paper reports a case-notes study of the criteria employed by UK clinicians, prior to the introduction of a purchaser-provider health care market into the UK National Health Service. Two child and adolescent psychiatrists rated the case notes of 24 in-patients, and 72 out-patients, matched for age and sex, according to symptomatology, social adversity and severity of behavioral and emotional impairment. The findings indicate that social adversity does not predict admission. Certain symptoms such as sexualized or severe antisocial behavior may even act to diminish the likelihood of admission. However, the principal finding is that, within a non-market, free health care system, the degree of clinical impairment suffered by the child or young person appears to be a prime determinant of the decision to admit.