Zinc Germanium Phosphide (ZGP) is one of those few reliable, efficient, high quality non-linear crystals that is beginning to dominate applications in a particular spectral region due to the unique properties of the material. A high non-linear coefficient (75 pm/V), good thermal conductivity (35 W/mK), relatively high Laser Damage Threshold (2-5 J/cm2 typically), and transparency with phase-matchability over the 2 μm – 8 μm range (and beyond) highlight the desirable properties of the material.