Skills and knowledge are crucial for finding good jobs and earning high incomes. This explains why, in spite of the increasing costs, most of us consider education as a valuable investment. However, new research at the Growth Lab - recently published in Science Advances - shows that just having valuable skills oneself is insufficient. What is as, or possibly even more, important as one’s own education is how our skills relate to the skills of the people we work with. Moreover, coworker complementarities help answer a number of old questions: Why can workers with the same education earn drastically different wages? Why do large cities pay such high wages? And why do workers earn higher wages in large establishments than in small establishments, even if they have similar skills?