A locally constructed developmental checklist, administered by teachers in a large southeastern Head Start program in suburban and rural areas, was used as an outcome measure to test the hypothesis that classroom quality is related to child progress in meeting developmental milestones. A two-level Hierarchical Linear Model was used to examine the influence of child-level demographic characteristics and classroom quality on child progress. In the child model (n=1,407 children), preassessment and child's age were associated with child postassessment scores. Three classroom models (n=80 classrooms) were estimated: (a) class-mean postassessment score as outcome, (6) pre- and postassessment slope as outcome, and (c) age-postassessment slope as outcome. The class-mean preassessment was positively associated with the class-mean postassessment. For the pre- and postassessment slope as outcome model, class-mean age and class size were both positively associated with pre and postassessment slope. The Individualizin...