This study examined the effect of a quasi-experimental project on fifth grade English learners' achievement in state-mandated standards-based science and English reading assessment. A total of 166 treatment students and 80 comparison students from four randomized intermediate schools participated in the current project. The intervention consisted of on-going professional development and specific instructional science lessons with inquiry-based learning, direct and explicit vocabulary instruction, integration of reading and writing, and enrichment components including integration of technology, take-home science activities, and university scientists mentoring. Results suggested a significant and positive intervention effect in favor of the treatment students as reflected in higher performance in district-wide curriculum-based tests of science and reading and standardized tests of oral reading fluency. (Contains 5 tables.)