In a probabilistic universe, different possible future events have different chances of occurring. We can think of the chance distribution at a time as a probability measure on the set of those possible worlds that are compatible with the actual history up to that time and the natural laws. Given this connection between chance and modality, our views about the shape of modal space have significant implications for the theory of physical chance. I argue that many influential modal theses, e.g. standard versions of counterpart theory, haecceitist forms of actualism, and well-known solution to various modal puzzles, all have very surprising and problematic consequence in the philosophy of chance. Consequently, we will either need to reject these modal theses or revise our views about chance.