Within the discourse of childhood sociology, children are extensively regarded as “social actors”, a perspective that underlines the importance of asking children about their lives and experiences. To actually carry out such research, however, raises several methodological, principal, ethical and practical issues, especially when the research is about vulnerable children as those in out-of-home care. In this article we discuss the issue of gate-keeping when conducting research with children in foster homes or residential care. As a concrete example we use experiences from a survey of living conditions among those children.  The research questions were: 1) How and by whom is gate-keeping carried out when research is conducted among children in out of home care? 2) How could one as a researcher relate to gate-keeping carried out by adults in the environment of the children versus children’s one will? 3) What impact does gate-keeping have on results, feasibility and in a wider perspective the knowledge production regarding children in social care? The article shows that researchers needs to encounter a chain of gate-keepers to be able to get access to the children, and often attrition is high in studies with children as informants. Adults can serve both as gate-keepers and gate-openers. Our conclusion is that children in social care can be reached for research purpose, but that it is time-consuming, challenging and as a researcher one is often faced with ethical dilemmas. It is clear that there has to be a balance between gate-keeping and gate-opening. In this balance, on the one hand, it is possible for children to talk to researchers when they wish to do so, on the other hand, children must be protected so they are not exploited as research objects.