The present study examined (1) whether children notice different causes for contagious illnesses, non-contagious illnesses, and injuries and (2) what information adults provide to children and to what extent this information is related to children's causal awareness. Studies 1 and 2 explored preschool teachers' and mothers' explanations of illnesses and injuries, and Studies 3 and 4 examined children's understanding of causality. The teachers and mothers frequently offered various kinds of information about illnesses and injuries to children. Explanations based on behaviour and life habits were most common. When explaining contagious illnesses, they tended to refer to contagion, while when explaining non-contagious illnesses, they sometimes mentioned inherited constitution. But mention of heredity was never observed for contagious illnesses and injuries. In Studies 3 and 4, 5-11-year-old children consistently denied a belief in immanent justice. For contagious illnesses, they appeared to notice that physical contact with contaminants make us sick. Older children's awareness appeared to become more differentiated and sophisticated. From middle childhood, they come to notice that inherited constitution plays some role in susceptibility to non-contagious illnesses.