Glass-ceramics have been investigated since the 1970s to integrate high-, intermediate-, and low-level radioactive wastes coming from reprocessing of nuclear spent fuel, nuclear decommissioning activities, legacy radioactive waste from non-fuel cycle activities, and industrial hazardous wastes. This talk summarizes some approaches used for glass-ceramic design and fabrication for waste immobilization applications, and examples of typically studied glass-ceramic systems are given, with an emphasis on the crystal chemistry of the designed ceramic phases. Finally, some newer characterization methods will be shown which provide additional insight to these heterogeneous materials, including X-ray nano computed tomography, projection X-ray imaging combined with localized small-angle and wide-angle X-ray scattering, and luminescence mapping using Raman laser excitation.