Programs that improve teaching effectiveness represent a core strategy to improve student educational outcomes and close student achievement gaps. This article compiles empirical values of intraclass correlations for designing effective and efficient experimental studies evaluating the effects of these programs. The Early Childhood Longitudinal…

This paper assesses the impact of welfare reform's parental work requirements on low-income children's cognitive and social-emotional development. The identification strategy exploits an important feature of the work requirement rules--namely, age-of-youngest-child exemptions--as a source of quasi-experimental variation in first-year maternal…

In observational studies, selection bias will be completely removed only if the selection mechanism is ignorable, namely, all confounders of treatment selection and potential outcomes are reliably measured. Ideally, well-grounded substantive theories about the selection process and outcome-generating model are used to generate the sample of…

The introduction to this Special Topic Collection has two parts. To provide background and context for the articles in the collection, Part 1 tells the story of the Early Childhood Longitudinal Study program at the National Center for Education Statistics. It offers an abridged history of this program and describes the designs of the two national…

Background/Context: Past research has examined many factors that contribute to the black-white achievement gap. While researchers have shown that teacher perceptions of students' academic ability is an important contributing factor to the gap, little research has explored the extent to which teacher perceptions of students' academic ability are…

Psychometric properties of 24 items from the fifth grade Early Childhood Longitudinal Study-Kindergarten Cohort Mathematics Teacher Questionnaire were investigated in a sample of 5,181 participants. These items asked teachers to report how often they had their classroom students engage in different mathematics content, skills and instructional…

Children participating in kindergarten programming across the United States are expected to perform at a higher level than ever before. Many of these children are unprepared and developmentally unready for the academic tasks that await them. Researchers have shown that an older age at the start of kindergarten is a predictor of academic…

Recently, researchers have begun to employ rigorous statistical methods and developmentally-informed theories to evaluate outcomes for students retained in non-kindergarten early elementary school. However, the majority of this research focuses on academic outcomes. Gaps remain regarding retention's effects on psychosocial outcomes important to…

Researchers have become increasingly interested in programs' main and interaction effects of two variables (A and B, e.g., two treatment variables or one treatment variable and one moderator) on outcomes. A challenge for estimating main and interaction effects is to eliminate selection bias across A-by-B groups. I introduce Rubin's causal model to…

Background/Context: Researchers, policymakers, and practitioners undoubtedly concur that missing school deteriorates student outcomes. And yet, in evaluating the deleterious effects of missing in-school time, empirical research has almost exclusively focused on absences, and the scant amount of empirical literature on tardiness has focused on…

This study examined the efficacy of a core kindergarten mathematics program, Early Learning in Mathematics (ELM), a 120-lesson program with four content strands: (a) number operations, (b) geometry, (c) measurement, and (d) vocabulary. The study utilized a randomized block design, with 129 classrooms randomly assigned within schools to treatment…

Recent federal, state, and district policies that have mainstreamed English language learner (ELL) students into general, English-only elementary school classrooms have raised questions among educational stakeholders about the widespread effects of these policies. Most research has focused on the outcomes of ELL students; almost nothing is known…

The authors explored how classroom gender composition moderated the relationship between having classmates with emotional and behavioral disorders (EBD) and peers' academic achievement in both kindergarten and Grade 1 classrooms. Given the behavioral and social-cognitive styles of girls, it was hypothesized that classrooms with a higher percentage…

The Early Childhood Longitudinal Study, Kindergarten Class of 2010-11 (ECLS-K:2011), is collecting information about the early educational experiences of a nationally representative sample of children who were in kindergarten or who were of kindergarten age in ungraded classrooms or schools in the 2010-11 school year. The data collection began in…

Professional development (PD) for early childhood educators has received increased attention as a means of bolstering young children's learning and development. Theory and research indicate that educators' characteristics play roles in both their own learning and that of children; however, little research has explored who participates in PD. This…