One of the most important assumptions about the operation of the contemporary foster care system is that caring for a child deprived of proper living conditions in their own family is temporary. The aim of a child’s stay in foster care is to rebuild the stability of the family and restore it to the child or—should that emerge as impossible—to regulate the child’s legal status and initiate the adoption procedure.The research objective is to determine to what extent care centres fulfil the assumptions of foster care temporariness and define mutual relations between variables significant for the fulfilment of this assumption. It also aims to determine differences between towns with district rights and country districts concerning the indicators of foster care temporariness. The study was conducted based on financial and material reports on the performance of tasks in the field of family support and the system of foster care in the province of Silesia. The study results show that, on average, family reintegration occurs in the instance of one in nine children placed in institutional foster care. At the same time, the adoption rate is depicted by a downward trend. Another phenomenon of concern is that an increasing proportion of children leaving institutional foster care are those who become independent. This means that the temporariness of institutional foster care is decreasing. Research also demonstrated that the indicators of deinstitutionalisation and intensity of foster care do not have a statistically significant impact on fulfilling the temporariness assumption at care institutions. The type of county, on the other hand, has a statistically significant effect on the fulfilment of adoption tasks.