This chapter argues that locality is a necessary condition for causal explanations to be commonsensical. It takes it as a requirement on an adequate physical theory that it be able to offer local causal explanations of all experimental outcomes. The chapter discusses how the demand for local causal explanation shaped classical physics. It introduces quantum physics in the context of a simple experiment, which although strange, can be explained locally. It specifies three refined common sense principles of locality. These principles are satisfied by classical physics and by the simple quantum experiment. The chapter also presents several quantum experiments that do seem to violate the principles and therefore defy common sense. It shows that common sense can be restored to quantum theory if we adopt the many worlds interpretation. The chapter also discusses the significance of our results to debates over the interpretation of quantum mechanics.