This study was part of the Promoting Science among English Language Learners (P-SELL) efficacy study, a research and development project that implemented a curricular and professional development intervention to improve science achievement of English Language Learners (ELLs) in urban elementary schools. The study used a cluster randomized control trial (RCT) design with 31 treatment schools and 32 control schools over a 3-year period. This study used a series of hierarchical generalized linear models (HGLMs) to examine science proficiency as measured by state high-stakes science assessment. The results indicated differences in science proficiency between the treatment and control groups in Years 2 and 3, but not in Year 1. The results demonstrate that an educational intervention based on the synergy of science and English language and literacy for ELLs is effective at increasing students’ science achievement. However, there may be a lag in improved student achievement as teachers gain familiarity with the new curriculum and adjust their teaching practices over time.
