This chapter discusses electronic structure of actinides (5f): thorium (Th), plutonium (Pu), and americium (Am). The linearized augmented plane-wave method has been applied to (100) and (110) surfaces in face-centered Th; there are two groups of surface state in each case: highly localized ones of f type lying above the Fermi level and less localized ones lying in the filled part of a band. Sphere-projected density of states for calculation with spin-orbit interaction, and electron charge density distribution contour map of Pu are shown. Integrated charges (number of electrons) contained within spheres, resolved into orbital components of Pu are tabulated. X-ray and high-resolution UV photoemission spectroscopy of the conduction band of Am metal directly reveal that the 5f electrons in Am are localized, in contrast to the 5f electrons in the lighter actinide metals.