A questionnaire study conducted with 774 children, aged 8 to 17 confirmed predictions that age is directly related to (a) the degree of probabilism, or uncertainty, within children's expectancies of encountering a variety of health problems, and (b) the level of perceived vulnerability to health problems. Data were obtained in 28 classes, 4 at each of 7 grade levels (3rd through 9th) within the schools of a large city. Equal numbers of classes were drawn from innercity and non-innercity areas. Findings reflecting significant SES effects were explained in terms of differential normative pressures and communications processes. (Author)