This paper studies learning among coworkers when incentives change. We use a simple principal-agent model to show that when workers are not fully informed on the global shape of the production function, (1) their effort choice changes over time as information is disclosed and processed and (2) changing incentives can trigger this learning process. We test this prediction using personnel data from an egg production plant in Peru. Exploiting a sudden change in the contract parameters, we find that workers learn from each other over the shape of the production function. This adjustment process is costly for the firm.