Developing quality relationships is recognised as an active ingredient for effective interventionswith young people in care. Essentially, care staff has the opportunity and capacity to positively influence the young person's experiences in care, through the positive relationships they form. This paper presents selectively on the findings of two separate but related qualitative Irish studies exploring relationship-based approaches in residential child care practice, fromthe perspectives of both residential child careworkers and young care leavers. Thirty-two professionals and four care leavers participated in either focus group or individual interviews. The findings are integrated in this paper with the wider literature on young people leaving care, with the aim of identifying core knowledge that is needed by service providerswho are taskedwith the support of young peoplemaking the transition out of care and towards independent living. In this paper we attempt to identify the knowledge base on relationship-building which is needed by care staff in order to carry out their role. It is argued that an explicit knowledge base is overdue now that the complex needs of young people in care are increasingly visible through advances in research and more recently the emerging literature concerning the personal testimonies of care graduates.