There is much consensus that knowledge is an important and valuable resource in many industries. In the context of organizational choice and decision-making, knowledge is valuable because it allows firms to make informed and better choices. This is particularly true for positive knowledge, i.e., knowledge about successes or above-average alternatives ("knowing what does work"). Indeed, one fundamental premise of rational accounts of choice is that knowledge always has a non-negative value. Using an n-armed bandit model, we demonstrate that while this is true for unique, non-recurring choices, it may not be true for recurring choices that allow for learning. With recurring choices, positive knowledge can hurt performance while the value of negative knowledge ("knowing what does not work") always remains non- negative The findings of our study have important implications for the study of choice and learning under uncertainty, learning from success and failure, and knowledge as strategic asset.