Radiation‐induced defects in Zr‐based fluoride glasses have been characterized using optical absorption and electron spin resonance (ESR) techniques. The optical absorption bands due to interstitial fluorine atoms, the F−2, FCl−, Cl−2centers, and Zr3+centers have been identified by correlating optical absorption and ESR measurements. Polarized bleaching experiments indicate that the hole‐type centers, and the Zr3+centers have anisotropic defect configurations. X‐ray excitation at 14 K generates a broad, asymmetric emission band at 337 nm (3.68 eV), which is assigned to a localized‐excited state similar to that for self‐trapped excitons in halide crystals. The intensity of the x‐ray induced emission provides further evidence that radiolysis defect production occurs in this material. The optical tail of the radiation‐induced Zr3+absorption affects infrared transmission. Evidence is presented that the CCl4reactive‐atmosphere process introduces a significant amount of Cl−(∼5%) in the glass.