Solar energy materials have properties tailored to meet requirements set by the spectral distribution, angle of incidence, and intensity of the electromagnetic radiation prevailing in our natural surroundings. Specifically, the optimization can be performed with regard to solar irradiation, thermal emission, atmospheric absorption, visible light, and photosynthetic efficiency. Materials for thermal and electrical conversion of solar energy in man-made collectors, as well as for energy-efficient passive design in architecture, are typical examples. This paper reviews solar energy materials with emphasis on the thermal applications of a variety of types. Electrical applications are given a more cursory exposition, the reason being that a systems perspective -rather than a materials perspective - is most fruitful in this case.