Much research on the experiences of parents of children with cancer has been conducted within a discourse of psycho-pathology, or has tended to see parents mostly as a proxy source of information on the well-being of their children. Using empirical data from semi-structured interviews with 20 mothers of a child with cancer, in one area of the UK, we draw on sociological literatures on motherhood, childhood, caring, and chronic illness to suggest a more helpful and informative way of understanding their experiences. We suggest that mothers, although not ill themselves, experience many of the consequences of chronic illness. Biographical disruption begins for them when they first notice something wrong with their child, and intensifies with diagnosis, altering their sense of self and their social identity. The diagnosis brings with it a set of new responsibilities and role expectations, including an obligation of 'proximity'-being physically close to their child at all times to provide 'comfort' and 'keep-watch'. For mothers, caring evokes an intense emotional interdependence with their sick child, and involves a range of technical tasks and emotional work, including acting as 'brokers' of information for their child and managing their cooperation with treatment. Managing these obligations was achieved at high cost to the mothers themselves, and resulted in severe role strain by compromising their ability to function in other roles, including their role as the mother of their other children. Against the backdrop of a severe and life-threatening illness, everyday concerns about their child's diet or appropriate discipline take on a new significance and carry a heightened potential for generating conflict and distress for mothers. In presenting their accounts, mothers draw on prevailing cultural discourses about motherhood, childhood and cancer, and these clearly influence the context in which they care for their child, and shape their reflexive constructions of their experiences. Caring for a child with cancer had many adverse implications for the quality of life of the women we studied. Mothers of a child with cancer warrant study in their own right, and such study benefits from interpretive perspectives.