Response to illness was studied in a group of 251 low-income mothers who brought a child to a pediatric clinic for treatment. Measures of illness and use of medical care services for the child constituted the dependent variables; social characteristics of the mother, and her health beliefs and attitudes served as the independent variables. The information was collected by means of personal interviews. A major determinant of seeking care was the presence of symptoms in the child. Age, number of children, beliefs about illness threat, and about the benefits of medical care also related to obtaining care. A measure of the scope of services used, however, was unrelated to illness, but positively related to both education and the mother's evaluation of physicians. With illness taken into account, situational barriers plus beliefs concerning illness threat and the efficacy of care become more important predictors of utilization of care. The beliefs are related to the mother's experience, education, and life situation. It was concluded that health beliefs interact with situational demands and constraints in relation to actions taken in the face of health threats.