A Public Laboratory is a fascinating, rich, insightful essay with many possible points of entry for a commentator. I will focus on one observation: nationwide systemic school reform as described by Liebman and Sabel should not have occurred, according to conventional political wisdom. By the same logic, the further reforms they predict and hope for are unlikely to transpire. But reform did occur and seems to be gaining in momentum; we need to develop a clearer understanding of why it did so in order to share even their cautious optimism.