In 1999, Texas Legislature mandated the Student Success Initiative to ensure all eighth grade students are on grade level in reading and mathematics. Although progress is evident, the achievement gap for English language learners remains. The purpose of this case study was to explore effective school practices that lead to closing the achievement gap. This qualitative study applies the two core functions of leadership for exercising influence and providing direction to answer the research question: How do the core functions of school leadership practices for implementing the Student Success Initiative requirements vary between English language learners and non-English language learners in high and low-performing middle schools? The comparison between the high-performing school and low-performing school brought forth key findings and identifies school practices for supporting secondary English language learners. The key findings for exercising influence on teachers were: 1) Effective school practices that influence teacher knowledge on how to identify students and their needs include: a) conducts a needs assessment.; b) analyze data; c) create differentiated ESL programs, d) place diverse groups of ELLs in differentiated ESL programs. 2) Effective school practices to influence teachers how to intervene include: a) accept teacher input and follow through on requests when planning interventions, b) target intervention needs; c) create differentiated interventions. 3) Effective school practices to influence teachers how to monitor include: a) analyze multiple types of data, b) measure student reading growth; c) measure student language proficiency, d) conduct walkthroughs to observe students. The key findings for providing direction to teachers established the following practices: 4) Effective school practices to provide direction to identify students and their needs include, a) develop and implement a school wide intervention plan, b) create a master schedule to implement differentiated ESL programs; c) model how to disaggregate data, d) develop and implement an individual plan for ELLs. 5) Effective school practices to provide direction to intervene include: a) assign ESL teacher to intervention groups, b) use data to drive intervention planning, c) measure growth in language and literacy, d) provide daily interventions, e) integrate language and literacy interventions in lessons. 6) Effective school practices to provide direction to teachers for monitoring include: a) measure growth of literacy and language development, b) triangulate multiple types of data, c) review intervention lessons during walkthroughs, e) provide daily interventions specific to student needs. / text