Persistent school non-attendance (PSNA) is a widely acknowledged problem. Family coaches work intensively with families where a child or young person (CYP) has persistently poor or no school attendance and there is unemployment or anti-social behaviour. Their work extends across different systems, which gives them a unique, multi-factored understanding of the phenomenon of PSNA in coaching families. The aim of this grounded theory (GT) study was to draw upon the experiences and perspectives of coaches in one UK local authority, to understand what helps and hinders successful intervention. A GT emerged, in which PSNA in coaching families was a "red flag," occurring when CYP felt unsafe. This was a product of the home environment not providing a secure base, parents having a diminished capacity and the CYP feeling that their situation was invisible. Successful intervention was relationship-based; improved the visibility of CYP; and increased parenting capacity. Intervention was constrained by conflicting systems that resisted or sabotaged change.