This study investigates the quality of collaboration in instructional teams and student achievement. The data was collected from 9,000 teachers through surveys and observations in Miami-Dade County public schools. The survey result showed that 90% of the teachers reported that collaboration with other teachers was helpful. Moreover, teachers found developing instructional strategies and reviewing formative assessments were the most helpful practices. The study also revealed that schools where the instructional teams engaged in better collaboration had students who had higher gains in math and reading achievements. In addition, better collaboration in the instructional team contributes to teacher improvement. While not focused on MLs, this study indicates that positive collaboration experiences in the instructional team not only cause an increase in student achievement but also improves teacher growth.