A student's middle school science experience strongly impacts their future science, technology, engineering, and mathematics interest. The Japanese lesson study (JLS) model strengthens the student's experience through a research-based, collaborative, multistep, teaching-centered process focused on transforming local instructional practices. The JLS model has seen very limited application to middle school life science classrooms. The six-year-long implementation of JLS to core standards in the seventh-grade life science curriculum at a Los Angeles area school serving a historically underrepresented population found large, gender-independent increases in student mastery of key science standards, increased teacher collaboration in the areas of lesson development and data analysis, and school-site reform yielding district and statewide recognition.