Malaria is a major cause of under-five mortality in Mali and many other developing countries. Malaria control programmes rely on households to identify sick children and either care for them in the home or seek treatment at a health facility in the case of severe illness. This study examines the involvement of mothers and other household members in identifying and treating severely ill children through case studies of 25 rural Malian households. A wide range of intra-household responses to severe illness were observed among household members, both exemplifying and contravening stated social norms about household roles. Given their close contact with children, mothers were frequently the first to identify illness symptoms. However, decisions about care-seeking were often taken by fathers and senior members of the household. As stewards of the family resources, fathers usually paid for care and thus significantly determined when and where treatment was sought. Grandparents were frequently involved in diagnosing illnesses and directing care towards traditional healers or health facilities. Relationships between household members during the illness episode were found to vary from highly collaborative to highly conflictive, with critical effects on how quickly and from where treatment for sick children was sought. These findings have implications for the design and targeting of malaria and child survival programming in the greater West African region.