The Child Treatment Research Unit (CTRU) based in the School of Social Work at Leicester University has, as its name implies, service, treatment and training functions. It has accumulated several years' experience of behavioural interventions on the Triadic Model with problem children and their families. The triadic approach—using behaviour modification in home settings—is designed to counter the apparent illogicality in removing a child from the setting in which the problem occurs, of attempting to modify his behaviour in isolation from those who may instigate and reinforce a large part of it and then returning him to the unchanged context in which the problems flourished. A method, behavioural casework, based upon behaviour modification and self-help principles, is described with regard to conduct problems. Procedures as used in the Unit, but more particularly in the natural or foster home-setting, are detailed and the results (which are very encouraging) tabulated.