The principle radiation damage effects occurring in optical materials, particularly those produced by energetic particles and gamma rays, are described phenomenologically. Included is a description of the basic processes whereby radiation interacts with non-metals. Emphasized are: 1) ionization induced electron and hole formation and migration processes and, 2) the displacement and ionization damage effects that are responsible for atoms being displaced from their normal lattice positions. In nonmetals, the principal radiation damage effect produced by these processes is the creation of color centers. In turn, it is shown that the radiation induced color center formation, as well as the changes that occurs after an irradiation is terminated, are described by a particularly simple theory. Radiation damage in transparent crystals and glasses is illustrated by measurements made with unique equipment fn making optical measurements during and after irradiation. One arrangement utilizes a 60 Co gamma-ray source and the other a 3.0 MeV electron accelerator. The illustrations include: 1) Measurements on F-center formation during irradiation--and the changes that occur after irradiation--on LiF, NaC1, and KC1 synthetic crystals. 2) Studies on the radiation induced F-center and Na metal colloid formation occurring in natural rock salt (NaCl) from potential radioactive waste repository sites. 3) The growth during irradiation and decay after irradiation of color centers in glasses irradiated at different temperatures. Lastly, the radioluminescence emitted during irradiation, as well as the absorption spectrum changes and the thermoluminescence emission that is observed when irradiated samples are heated, is illustrated by studies on natural quartz.