Study designed to further our understanding of the pathogenesis of asthma exacerbations in children. Children enrolled in the study (n=217) were all asthmatic and primarily Hispanic white. The children were followed for 18 months until they experienced an asthma exacerbation or completed the follow-up without an exacerbation. The time to the first asthma exacerbation was considered the outcome. The acute and convalescent immune phenotype of each asthma exacerbation was documented.