Workers' reciprocal behavior is one argument used to explain why firms invest in employee human capital. We explore the relation between firm-sponsored training and reciprocity by providing evidence that workers reciprocate employer training investments by making greater effort. Using a field experiment with random assignment to a training program, we show that reciprocal workers have significantly higher performance than their non-reciprocal peers after participation in the training course. This result suggests that reciprocal workers exert greater effort in response to the firm's investment.