State education departments, in discussions with Regional Educational Laboratory (REL) Southeast, identified low reading achievement as a critical issue for their students and expressed an interest in identifying effective strategies to promote the foundational skills in young students that might improve reading achievement. The Mississippi State Department of Education has focused specifically on interventions that might enhance students' vocabulary knowledge. Kindergarten PAVEd for Success (K-PAVE) was selected to be tested in Mississippi for three reasons. First, there were only a small number of vocabulary interventions appropriate for this age group to be considered. Second, among these, PAVE--the preschool version of the intervention--was the only one for which an impact study had been completed that provided some evidence of effects. Third, K-PAVE was the only curriculum that had developed teacher training materials and a training protocol, which meant that it could be implemented with sufficient fidelity across a variety of districts and school settings. The primary research question for the study addressed the impact of K-PAVE on kindergarten students' expressive vocabulary. Secondary research questions addressed the impacts on kindergarten students' academic knowledge and listening comprehension. Although the study was concerned primarily with the impacts of K-PAVE on students, impacts on intermediate classroom instruction outcomes were also assessed to provide context for understanding potential impacts on students. The study addressed research questions about impacts on classroom instruction in vocabulary and comprehension support, instructional support, and emotional support. Finally, the study examined whether the introduction of K-PAVE had the unintended consequence of reducing the time spent on areas of literacy instruction other than vocabulary and comprehension (such as phonological awareness, alphabet knowledge, print concepts, and decoding). The study found that kindergarten students in schools using K-PAVE as a supplement to the regular literacy instruction performed better than kindergarten students in control schools on the Expressive Vocabulary Test-2 administered at the end of the school year. The study also found that kindergarten students in K-PAVE schools performed better than students in control schools on the measure of academic knowledge administered at the end of the year. K-PAVE caused a positive and statistically significant impact on one of the three kindergarten classroom instructional practices examined: vocabulary and comprehension support, which includes introducing vocabulary words during read-alouds, introducing vocabulary words throughout the school day, asking higher order questions during read-alouds, and providing comprehension support during book read-alouds. Appendices include: (1) Mississippi Counties with Study Schools, by County; (2) Statistical Power Analysis; (3) Random Assignment; (4) Recruitment and Random Selection of the Student Sample; (5) Comparison of Students Missing and Not Missing Baseline Assessment; (6) Classroom Observation Measures for Impact Evaluation; (7) Teacher Survey; (8) K-PAVE Fidelity Observer Handbook and Training Fidelity Checklist; (9) Data Collection Procedures; (10) Data Quality Assurance Procedures; (11) Model Specifications; (12) Flowchart Illustrating Sample Attrition from Data Collection; (13) Missing Data Imputation; (14) Sensitivity Analyses; (15) School, Teacher, and Student Covariates; (16) List of K-PAVE Materials Provided to Teachers; (17) Sample Weekly Unit from K-PAVE Program; (18) List of the 240 K-PAVE Target Words; (19) K-PAVE Teacher Training Agenda; (20) K-PAVE Teacher Phone Follow-Up Agenda; (21) Sample Means and Standard Deviations for Student and Classroom Outcome Measures, by Intervention Status; (22) Checking Model Assumptions; and (23) Translating Impacts on Students into Age-Equivalent Differences in Posttest Outcomes. (Contains 53 tables, 16 figures, 1 map, 3 boxes, and 86 footnotes