This study explores the influence of cognitive development and health self-perception on Brazilian students' beliefs on the causes of health and illness. Ninety-six randomly selected elementary and junior high school students from two schools in the north area of Rio De Janeiro County were interviewed individually by an investigator. Subjects who were classified as functioning at the concrete operational level and as having a good health self-perception attributed health and illness significantly less to uncontrollable events (e.g. "luck"), immanent justice (e.g. "obedience"), and powerful others (e.g. "doctor care") than did their respective counterparts. The overall findings of this investigation were congruent with the age, school grade level, and cognitive development literature of the areas, suggesting that there seems to be more cross-cultural commonalities than differences in children's causal attribution for health and illness. Health promotion initiatives should teach children to develop not only a sense of self-responsibility toward their own health, but also a realistic awareness of the factors that affect both health and illness (Contains 7 references.) (RJM)