Abstract: Suppose that one has a choice between two otherwise identical restaurants: one is close and the other is far. Closer is often better; it is rational to care about what is proximate and hence to choose the closer restaurant. Now suppose that one has a choice between two different medical facilities: one is close but average, and the other is far but superb. On plausible assumptions about the welfare effects, it is not rational to choose the closer medical facility. Proximity bias can be found when people are willing to suffer serious welfare losses in terms of (say) health or wealth in return for modest welfare gains in terms of proximity. In extreme cases, proximity bias leads people to stay where they are. Proximity bias can be seen as a form of present bias, or even as the thing itself, though it often has distinctive characteristics (including overestimation of the intrapersonal welfare costs of getting from one place to another). Some extreme forms of proximity bias can be counted as pathological ("hodophobia"). There is clear evidence of the importance of proximity, and suggestive evidence of proximity bias, in the contexts of medical care; vaccination; eviction; voting; and public assistance. Policy implications include the potentially large effects of increasing (or reducing) proximity or making it less (or more) salient, perhaps through the use of online alternatives or other forms of choice architecture.