All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad (saw) is His slave and Messenger. If by this legal adoption you mean that the child is traced back to those who nurture him and he becomes their child who inherit them if they die and the like, then this adoption is forbidden in Islam. However, if you mean by guardianship and adoption according to the Shareeah, is just nurturing the child and being kind to him without adopting him as ones own child, then this is desirable and this is among the good morals when there is a need for him, and in this case there is no difference if the child is from Muslim parents or non-Muslim parents. For more benefit, please refer to Fataawa 84422 and 82371.Allaah Knows best. (Source: islam_web) Classified in Women and Family > Rights of Children