PISA is an extremely influential large-scale assessment, and its "policy lessons" are being incorporated in a range of nations all over the world. In this paper I argue that not only is PISA influencing policies and practices, but also that "seeing like PISA" is becoming a widespread phenomenon. Globally, education administration is now characterized by an intense focus on output measurement, a highly competitive environment heightened by national and international rankings, and an economic and instrumentalist approach to education and education reform. Using James Scott's account of 18th Century German forestry practices as a parable, this paper suggests that "seeing like PISA" could have far reaching and damaging effects. The paper proposes the following: first, understanding PISA as a "project of legibility" enhances our appreciation of its purposes and possibilities. Second, PISA is much more than a "representation" of existing conditions, but is creating new conditions--in other words, it is not descriptive but performative; and, finally, "seeing like PISA" is bringing about deep-rooted changes, and it is likely that the effects will be very long-term. Some of these effects may only manifest themselves in the next fifteen or twenty years; and, by then, the possibilities of redressing some of the ill effects may be very limited.