This book argues that objective chance, or probability, should not be understood as a metaphysical primitive, nor as a dispositional property of certain systems (“propensity”). Given that traditional accounts of objective probability in terms of frequencies are widely agreed to be also untenable, there is a clear need for a new account that can overcome the problems of older views. A Humean, reductive analysis of objective chance is offered, one partially based on the work of David Lewis, but diverging from Lewis’ approach in many respects. It is shown that “Humean objective chances” (HOCs) can fulfill the role that chances are supposed to play of being a guide to one’s subjective expectations. In a chapter coauthored by Roman Frigg, HOC is shown to make sense of physics’ uses of objective probabilities, both in statistical mechanics and quantum mechanics. And in the final chapter, the relationship between chance and causation is analyzed; it is argued that there is no direct connection between causation and objective chance, but that, instead, causation is related to subjective probability.