Children taken into care and custody are arguably the most vulnerable and problematic groups within the wider debate and responses developing to the 'troubled families' agenda in England. They represent what the state most wants to avoid when it intervenes in the life of a family. This article is based on an analysis of the service involvement and needs of the 196 children taken into care or custody over a three year period (2008-2011) in one city local authority in England. The research was undertaken to inform the response to prevention of entry into care and custody which was the original focus of the most intensive part of the troubled families programme in the city. Interviews with 10 senior professionals from a range of agencies involved in setting up this local programme, explored the way the emerging troubled families agenda was shaping ideas about the understanding of and response to the needs of these children and their families. Key findings of the study illustrate the range and complexity of need as well as the sequence and amount of agency involvement. Professionals were often critical of the thinking behind the troubled families agenda, but were positive and creative about new ways of working with these families.