This dissertation used nationally representative data from the Early Childhood Longitudinal Study, Kindergarten Class of 1998-99 (ECLS-K) to explore relationships between full-day kindergarten classroom factors, family socioeconomic status (SES), and public school children's gains in reading achievement and academic engagement over their first formal year of schooling. Specifically, the study focused on two aspects of kindergarten classroom factors that could maximize the additional time provided by full-day programs: instructional resources (i.e., class size and instructional aides) and instructional practices (i.e., time allocation across subject areas, grouping strategies, and instructional skills and activities). Two-level hierarchical linear modeling (HLM) analyses (i.e., full-day kindergartners nested within public schools) were conducted to investigate the effects of school-averaged classroom factors on children's reading and academic engagement gains over the kindergarten year, as well as possible effects of school- averaged classroom factors on the relationship between children's SES and the aforementioned outcomes.

The study identified multiple classroom factors associated with overall differences in full-day kindergartners' average reading gains. Specifically, results suggested that increases in reading instructional time, decreases in class size, and a balance in the frequency of discrete literacy skills and comprehension-based skills could help to accelerate reading gains during the kindergarten year. This study did not find evidence to support concerns that full-day kindergarten programs might harm children's academic engagement because of an overemphasis on academics. Instead, full-day kindergartners' academic engagement tended to remain constant across the kindergarten year and did not vary in relation to most instructional practices. Results indicated that full-day kindergartners demonstrated increased academic engagement in schools that had instructional aides working at least one hour per day with kindergartners.

This study also found that the effects of family SES did not vary between schools, so average classroom resources and practices did not influence differentially the reading achievement gains or the academic engagement gains of students from different SES backgrounds. In sum, this dissertation helps to provide some of the first evidence on how full-day kindergarten programs might structure instructional resources and time-related instructional practices in ways that increase children's reading achievement and academic engagement.