The longitudinal analyses had two primary objectives. The first was to characterize patterns of functional lung development in Black children from three to 13 years of age and relate these patterns to potentially influential factors such as (a) wheezing and non-wheezing associated LRI experience during the infant (ages 0 to two) and preschool (ages two to five) years, (b) ages of occurrence of first and subsequent LRI episodes, and (c) respiratory syncytial virus etiology of LRI. Potentially confounding factors included prenatal and childhood exposure to environmental tobacco smoke and allergies. The second objective was to determine the degree to which spirometric parameters 'track' for individual children and for populations of children over the interval from three to 13 years of age. This objective required assessment of the degree to which spirometric evaluations during the preschool years were predictive of later lung function.