Two preliminaries: US experience points to the unprecedented challenge of the rapid, drastic energy transition we face, and the labor needed to accomplish it should regarded as a cost, not a benefit. This chapter thus encourages skepticism regarding claims that the cost of meeting carbon goals will be minimal and proposes questions that should be asked of optimistic studies. The most reliable analyses draw on integrated assessment models, which show we can achieve a two-thirds chance of limiting warming to 2° at moderate cost only by greatly overshooting corresponding carbon budgets, followed by decades of negative emissions using yet-to-be developed carbon removal technologies. Not predicating policy on these technologies, however, results in very high costs. Even so, these models don’t include the likelihood that much of the existing capital stock will be uneconomic to operate at high carbon prices, a potential source of enormous disruption. The closest analogy we have is the post-1989 shock in Eastern Europe when economic opening caused widespread shutdowns. It is important to be honest about costs: rosy forecasts are unconvincing, fail to prepare us for the problems we’ll need to solve and obscure the political economy of policy change.