The current status of our understanding of the rheological structure of Earth's interior from a mineral physics point of view is reviewed. The rheological structure of the lithosphere–asthenosphere system is discussed in detail as well as the rheological structure of the deep mantle and the inner core. The inferred rheological structures depend critically on the temperature, water content, grain size and stress as well as the constitutive relations that control the dependence of rheological properties on these variables. These variables can be inferred for the shallow portions of Earth and some detailed analyses of the rheological structures there are presented including the regional variation in the rheological structure of the lithosphere. In contrast, temperature, water content and grain size are poorly known for Earth's deep interior. In addition, some of the important material parameters for deep Earth materials that determine the sensitivity of the rheological properties on these variables are not well constrained. Consequently, the inference of the rheological structure of Earth's deep interior can only be made with large uncertainties. In these cases, emphasis is placed on the basic framework by which rheological structures of Earth may be inferred from mineral physics rather than on specific models.

Keywords lithosphere, asthenosphere, partial melting, phase transformations, water, grain size.