Mistakes happen, all will. agree, but whether mistakes exculpate, mitigate, or remit not a whit from culpability is much in doubt. The law's mistake course, replete with rules, often leads to conundrums and dead ends; moreover, there is evidence that ordinary citizens follow a very different course. Through three experiments, where a host of mistake-and culpability-related variables were manipulated, commonsense justice's story is brought to light. In this story, mistakes are seen socially and contextually, and not just as a function of a defendant's actus reus and mens rea. Though the defendant's intent is central, this variable interacts with the culpability of others, the harm, the case, the type of mistake, the reasonableness of the mistake, and negligence for bringing the mistake about. In the analysis of mistake, it is the commonsense story, not the law's, that is most complex and contextual and the one that involves the weightier calculus of culpability.