This study responds to regional and national needs by examining the impact on students' English language proficiency of a particular set of ELL-specific classroom materials in combination with a specific teacher professional development program. The classroom materials used in this study, entitled On Our Way to English (OWE), were authored by David Freeman, Yvonne Freeman, Aurora Colon Garcia, Margo Gottlieb, Mary Lou McCloskey, Lydia Stack, and Cecilia Silva and were published in 2003 by Rigby. According to the publisher, OWE is a comprehensive English curriculum for elementary classrooms (grades K-5) developed to provide ELL (English language learner) students with simultaneous access to English oral language development, comprehensive literacy instruction, and standards-based content area information in science and social studies (Freeman et al. 2003). The professional development program, entitled Responsive Instruction for Success in English (RISE), was written by Clara Amador-Watson and published in 2004 by Harcourt Achieve. RISE is a professional development program designed to meet the needs of K-5 teachers by providing them with sustained adult learning opportunities to acquire the knowledge and skills to support ELL students in language and literacy learning. RISE is intended to be delivered to teachers in eight separate, core modules. The study addresses one confirmatory research question and three exploratory questions. The confirmatory question addressed is: Does implementation of OWE in conjunction with the use of RISE have a significant impact on the acquisition of English language skills for ELL students as measured by the IPT composite score (based on subsection scores for listening comprehension, reading/vocabulary comprehension, and writing)? The exploratory questions are: (1) Does the combination of OWE and RISE have a significant impact on teacher-reported student engagement with ELL-specific educational materials?; (2) Does the combination of OWE and RISE have a significant impact on teacher-reported instructional practices (differentiated instruction, sheltering instruction, receptive and expressive language instruction, reading instruction, and writing instruction)?; and (3) Does the combination of OWE and RISE have a significant impact on teacher-reported instructional responsiveness and assessment practices (modification of instruction or teacher responsiveness, student-centered instruction, and use of assessments)? Schools in the Central Region states with the largest percentages of Spanish-speaking ELL students in the elementary grades--Colorado, Kansas, and Nebraska--were recruited and randomly assigned using a 2:1 ratio to the intervention group (34 schools) or the control group (18 schools). To understand the instructional practices used with ELL students at these sites, the authors examined online teacher logs, site coordinator surveys, and interview data. The results revealed that the instructional practices used with ELLs by intervention and control teachers were similar, although teachers in the control group were significantly more likely than teachers in the intervention group to self-report using graphic organizers with their ELL students. Between-group variance in the number of teacher-reported hours of English language development instruction with ELL students was not statistically significant. Confirmatory impact analyses estimated the mean difference between intervention and control groups on student acquisition in English, as measured by a composite of the listening, reading, and writing sections of the IPT ("IPT Testing System" 2005). All native Spanish-speaking ELL students receiving instruction from a study teacher on the day of testing in spring 2010 (Year 2) were included in the student sample. This sample included 2,612 students nested within 52 schools. Intervention and control groups were compared to determine whether the groups differed on school-level characteristics, including the percentage of students eligible for free or reduced-price lunch, school size, the percentage of students in different racial/ethnic groups, and location. A statistically significant difference was found between the percentages of White and Hispanic students; this variable was included as a covariate in the impact analysis model. The impact analysis revealed no statistically significant difference between the composite IPT scores of students in the intervention group (who were taught by teachers trained in RISE and who used OWE materials) and students in the control group. The exploratory analyses revealed no statistically significant differences between the intervention and control groups. The combination of OWE and RISE did not have a significant impact on teacher-reported student engagement in ELL-specific educational materials, teachers' self-reported instructional practices, or teachers' self-reported instructional responsiveness and assessment practices. Appended are: (1) Description of Interventions and Instructional Models Used in Participating Schools; (2) Design Assumptions and Power Analysis; (3) Teacher Characteristics; (4) Validity, Reliability, and Scoring of Language Acquisition Outcome Measure; (5) Survey Instruments; (6) Implementation of the Interventions; (7) Survey Scales; (8) Baseline Equivalence, Confirmatory Impact, Sensitivity, and Exploratory Analysis Model Specifications; (9) Variance Components; (10) Preliminary, Impact and Sensitivity Analyses; and (11) Exploratory Analyses. (Contains 59 tables, 3 figures and 46 footnotes.)