 The Childhood Asthma Management Program Continuation StudyPhase 2 is a 3.25 year observational follow-up study of the children enrolled in the Childhood Asthma Management Program CAMP randomized trial. CAMPCS2 is a multicenter National Heart, Lung and Blood Institute program. The objective of the CAMPCS2 is to determine the consequences of childhood asthma and its treatment on asthma outcomes in young adulthood. This separate ancillary study will extend the core CAMPCAMPCS work by focusing on progression of airway obstruction in childhood asthma to evaluate mechanisms of progression and describe the differences in the four separate patterns in airway obstruction that have evolved over time. The four patterns of airway obstruction which have been identified are as follows: 1 abnormal obstruction present in early childhood which remained abnormal LowLow group and 2 initially normal ratios, which worsened into the abnormal range over time NormalLow group. These patterns with unfavorable outcomes can be compared to two other patterns with favorable outcomes: 3 initially abnormal ratios improving with time LowNormal group and 4 normal ratios throughout follow-up NormalNormal group. 