IT IS IMPORTANT that we ask as many questions as we can about a child's environment. In clinical practice, as in pediatric research, one learns a great deal by asking the right question. We have all been taught that the patient's history provides the answer or diagnosis 95% of the time. In the case of pediatric illnesses such as lead poisoning and asthma, the comprehensive environmental history provides a window into a child's world, allowing one to identify environmental hazards to health that might not be discussed otherwise.