This study explores the impact of teacher collaboration on student achievement using longitudinal data from elementary schools. Researchers found a strong correlation between the quality of a teacher’s colleagues and their students’ academic performance, suggesting that teachers learn from each other. The study revealed that when teachers have more effective peers, their students tend to achieve higher test scores in math and reading. This effect is particularly pronounced for less experienced teachers and persists over time. The study highlights the importance of peer learning among teachers and its positive impact on student achievement, suggesting that schools should prioritize opportunities for teachers to learn from each other to improve overall student outcomes.