The fundamental condition of the healthy growth for a child is being grown up in a family environment. It is basically work for the mother and father to provided a suitable environment for the child and meet modelling care and affection needs. If the parents do not exist or they fail in their duty, the state will undertake caring for the child by means of some own institutions. In this area called child welfare, the institutional care is one of the oldest service kinds. In the child's growth years, the relations between the child and the mother is important. That is the most Important inconvenience of the institutional care because these kind relations could not be established in these places. Therefore it was desired that there should be a family where the child would grow up in. The foster family care is a child welfare service that will provide the family life for the child who had to leave his or her biological family because of any natural or legal reason. This research aimed at developing proposals to contribute to spread this kind care in Turkey by researching the theoretical and legal fundamentals of foster family care. The concept of foster family care became accepted in Turkish Law in Article 273 of Civil Law in 1926. Nevertheless because the public could not be informed about foster family care properly and sufficiently and the institution that would put forward this welfare was deprived of the necessary equipment. In the first part of the research; the aim, definition, fundamental elements, varieties of foster family care and different sides from similar180 institutions were analysed. The success of the foster family care is dependent on that the suitable child to this care was settled in suitable family -it means that the child security was provided-. However after the child was settled in the foster family, the interaction between the child and the biological family or the child and the foster family must be directed. At this point, the function of the social-worker is very important. In this context, in the second part of the research, the psycho-social bakcground was analysed. The foster family care is a legal institution that was devoted to the dependent children defined by laws. It is a child welfare service to take the child from his or her biological family and to settle in a foster family. Authority and responsibility of sides were organised with statutes in this period. In the third part of the research, the legal fundamentals of the foster family care were analysed in international and Turkish Laws.