Data were collected from July 6, 1992, through January 28, 1994. Data collection forms for each class or group of children were mailed to participating facilities each week. These forms were preprinted with the names of the facility, group, and children. Providers were asked to record each child's daily attendance as present, absent, not scheduled to attend, or no longer enrolled and to record any reported visits to health care providers. We also asked providers to obtain information from parents about illness episodes during periods children were not scheduled to attend and during unexplained absences. Providers recorded signs and symptoms they observed directly and diagnoses and illness information reported to them by parents. They selected 1 or more codes for each sign or symptom from a list of coded definitions. These were based, in part, on national criteria for excluding children from child care13 and were expressed in terms familiar to most laypersons. These signs and symptoms included specific conditions such as fever, diarrhea, vomiting, headache, rash, runny nose, sore throat, swollen glands, cough, earache, difficulty breathing, mouth sores, mouth sores with drooling, pinkeye, pinkeye with pus, jaundice, head lice, and worms, as well as nonspecific conditions such as irritability, decreased activity, and decreased appetite.