The three target articles provide examples of intervention studies that are excellent models for the field. They rely on rigorous and elegant designs, the interventions are motivated by attention to underlying theoretical mechanisms, and longitudinal designs are used to examine the duration of effects of interventions that occur. When studies are…

The authors reflect on findings from three studies of different approaches to reading intervention (Al Otaiba et al., Denton et al., and Miller et al., all found in this issue). It is argued that the science of interventions for reading disorders is advanced and that these and other related studies provide a strong evidence base for guiding…

Research designs in which clusters are the unit of randomization are quite common in the social sciences. Given the multilevel nature of these studies, the power analyses for these studies are more complex than in a simple individually randomized trial. Tools are now available to help researchers conduct power analyses for cluster randomized…

Experimental evaluations are increasingly common in the U.S. educational policy-research context. Often, in investigations of multifaceted interventions, researchers and policymakers alike are interested in not only "whether" a given intervention impacted an outcome but also "why". What "features" of the intervention led to the impacts observed,…

In this article I review the use of randomized field trials to evaluate school voucher interventions. I argue that although estimates of the effect of the voucher offer on achievement are unbiased in these trials, more specific interpretations such as the effect of attending private school may be difficult to obtain. I discuss several evaluation…

This article reports the outcomes of an experimental evaluation of "Read Well Kindergarten" (RWK), a program that focuses on the development of vocabulary, phonological awareness, alphabetic understanding, and decoding. Kindergarten teachers in 24 elementary schools in New Mexico and Oregon were randomly assigned, by school, to teach RWK or their…

Field experiments that involve nested structures frequently assign treatment conditions to entire groups (such as schools). A key aspect of the design of such experiments includes knowledge of the clustering effects that are often expressed via intraclass correlation. This study provides methods for constructing a more powerful test for the…

This randomized, controlled field trial estimated the causal impact of a technology-based geometry curriculum on students' geometry achievement, as well as their attitudes toward mathematics and technology. The curriculum combines learner-centered classroom pedagogy with individualized, computer-based student instruction. Conducted over a 3-year…

This article examines the effectiveness of four elementary school math curricula: (a) "Investigations in Number, Data, and Space"; (b) "Math Expressions"; (c) "Saxon Math"; and (d) "Scott Foresman-Addison Wesley Mathematics" ("SFAW"). These curricula are distinct from one another and represent many of the diverse approaches used to teach…

A meta-analysis of vocabulary interventions in grades pre-K to 12 was conducted with 37 studies to better understand the impact of vocabulary on comprehension. Vocabulary instruction was found to be effective at increasing students' ability to comprehend text with custom measures (d = 0.50), but was less effective for standardized measures (d =…

Prior research estimating the effect of Catholic schooling has focused on high school, where evidence suggests a positive effect of Catholic versus public schooling. In this article, we estimate the effect of attending a Catholic elementary school rather than a public school on the math and reading skills of children in kindergarten through fifth…

As an example of how the effectiveness of well-designed laboratory interventions is often diffused in the field, we examined the effects of a motivation intervention on students' perceptions and learning. The intervention proved to be more effective in the laboratory (g = 0.45) than the field (g = 0.05) in enhancing subsequent motivation. We…

In this 1-year experimental study of 254 students across 27 high-poverty preschool classrooms in an urban setting in the northeast, use of a technology-based prekindergarten literacy curriculum in addition to the district curriculum was compared with the use of the district curriculum alone. Results indicated no main effects for the experimental…

As investments in K-12 math and science professional development programs expanded over the past decade, researchers and policymakers have questioned whether and how such programs work to improve student learning. This article summarizes the current knowledge-base and offers a theoretical framework researchers can use to design studies that…

Inattention is often associated with reduced response to reading intervention. This study explored attention as a predictor of individual variation in response to a free-access Web-based literacy intervention, ABRACADABRA (http://abralite.concordia.ca) in typical Grade 1 children. A randomized control design was used to contrast two interventions,…