This article presents a metaphysical approach to the interpretation of the role of things-in-themselves in Kant’s theoretical philosophy. This focuses upon identifying their transcendental function as the grounding of appearances. It is interpreted as defining the relation of appearing as the grounding of empirical causality. This leads to a type of dual-aspect account that is given further support through a detailed examination of two sections of Kant’s first Critique. This shows the need to embed this dual-aspect account within a two-perspective (...) framework. The resulting picture is contrasted with the main rival theories and objections are addressed. (shrink)