Acute childhood illness is a universal experience for children and families. This paper presents the central process of a Glaserian grounded theory study which explored family management of acute childhood illness at home. Twenty-nine interviews were conducted with 15 families of children 0-9 years of age. Constant comparative analysis generated the substantive grounded theory 'Containing acute childhood illness within family life'. This informal social rule was identified from families' persistent desire to do the right thing, for their child and in the eyes of others in social life. Families perceived that they were expected to contain illnesses which are defined as minor and to seek medical help for 'real' illnesses. Considerable uncertainty was evident around defining the illness and the legitimacy of seeking medical help. Their concern with the latter indicates doctors' role as moral agents for parents' behaviour, directing the containment of acute childhood illness.