Several pressing issues call for institutions charged with the responsibility to educate prospective teachers to rethink their model of teacher preparation to better address the educational needs of English Language Learners (ELLs). It is projected that by 2025 one in four students in the U.S. will be from homes where a language other than English is spoken (NCES, 2006). For at least thirty years, the achievement of ELLs has lagged behind that of native English speakers in science and literacy (Buxton, 2006; Lee & Luyxk, 2006; NCES, 2006). In 2010 report, the National Academy of Science identified improving the preparation of teachers to teach science to ELLs as a national priority that would increase the successful participation of underrepresented minorities in STEM careers and degree programs (NAS, 2010). This paper describe the findings of a research and development project that involved science education faculty at three universities in developing and implementing an experimental science teacher education program to prepare pre-service teachers to use research-based instructional strategies in science teaching to improve the science learning of ELLs. A quasi-experimental study was used to examine the impact of the experimental program on 85 student teachers' instructional practice and compared with the practice of 50 student teachers who participated in the control "business as usual" program. The results showed that experimental group student teachers implemented significantly more ELL-responsive practices while they taught science during their clinical practices than control group student teachers.