In Anaxagoras’s system, something is qualified as, e.g. hot when it has within its constitution parts or shares of the relevant Opposite, e.g. the Hot, in preponderance over parts of other Opposites. Thus objects overlap constitutionally with the properties that qualify them. The chapter argues that Plato inherits Anaxagoras’s model of overlap, develops it, and makes it central to his own metaphysics. But it also shows that Plato is aware of some of the model’s shortcomings, and of the formidable difficulties which emerge specifically when the model is combined with his theory of Forms. The chapter examines some of these difficulties, pertaining to parthood, structure, and complexity, focusing on arguments that are milestones in Plato’s thought, such as the Partaking Dilemma in the Parmenides and the Third Bed Argument in the Republic.