We examine the relationship between job security and productivity in a fixed wage worker­firm relationship facing match quality uncertainty. The worker’s action affects both learning and current productivity. The firm, seeing worker behavior and outcomes, makes a firing decision. As bad news accrues, the firm cannot commit to retain the worker. This creates perverse incentives: the worker strat egically slows learning, harming productivity. We fully characterize the unique equilibrium in our continuous time game. Consistent with some evidence in organizational psychology, the relationship between job insecurity and productivity is U shaped: a worker is least productive when his job is moderately secure. (JEL J23, J24, J63, M51)