Perhaps one of the chief objections to open future views is that they must deny a principle we may call “Retro-closure”: roughly, if something is the case, then it was the case that it would be the case. Certain theorists, however—supervaluationists and relativists—have attempted to maintain both the open future view, and Retro-closure. In this chapter, the author argues (with Brian Rabern) that this combination of views is untenable: we must take our pick between the open future and Retro-closure. They argue that this combination of views results either in an unacceptable form of changing the past, or instead implausibly rules out the (former) existence of an omniscient being. In the appendix to this chapter, Todd argues that we can plausibly do without the Retro-closure principle, and that the principle, while intuitive, is not nearly so obvious as many have seemed to suppose.