About half of the children who have been admitted for day-treatment or residential treatment appear to have serious mental problems long after their discharge. However, the other half of these children appear to develop relatively well. This article gives an overview of the research on factors which predict the long term outcome of these children. In the research literature there appears to be a consensus on the predictive value of eight factors, which are discussed in some detail. It appears that these factors can mainly be covered by (1) factors pertaining to the amount and intensity of the problems at admission (e.g. diagnosis, organicity, intelligence); and (2) factors of the postdischarge period (e.g. aftercare, family environment). Although their importance is without question, the precise mechanisms through which these prognostic factors operate are largely unknown. Regarding this, some conceptual and methodological problems are discussed, including difficulties in operationalizing these factors, their interrelationships and the possibility of chain reactions. Also conclusions are drawn with respect to the clinical relevance of the findings.