This study reports 2 years of findings from a randomized controlled trial designed to replicate and demonstrate the efficacy of an existing, successful professional development program, the Pathway Project, that uses a cognitive strategies approach to text-based analytical writing. Building on an earlier randomized field trial in a large, urban, low socioeconomic status (SES) district in which 98% of the students were Latino and 88% were mainstreamed English learners (ELs) at the intermediate level of fluency, the project aimed to help secondary school students, specifically Latinos and mainstreamed ELs, in another large, urban, low-SES district to develop the academic writing skills called for in the rigorous Common Core State Standards for English Language Arts. The Pathway Project draws on well-documented instructional frameworks that support approaches that incorporate strategy instruction to enhance students' academic literacy. Ninety-five teachers in 16 secondary schools were stratified by school and grade and then randomly assigned to the Pathway or control group. Pathway teachers participated in 46 hr of training to help students write analytical essays. Difference-in-differences and regression analyses revealed significant effects on student writing outcomes in both years of the intervention (Year 1, d = 0.48; Year 2, d = 0.60). Additionally, Pathway students had higher odds than control students of passing the California High School Exit Exam in both years.