The period 1970-1975 has been one of unusual activity in the field of infrared materials. Driven primarily by the need for highly transparent lens and window elements in high power laser optics, significant advances have been made in the quality, physical strength and size of a variety of materials and in particular the alkali halides, alkaline earth fluorides, zinc selenide, and for use in fiber optics, fused silica. The state-of-the-art of these materials is outlined, the basic physical processes that determine their optical and mechanical limits are reviewed, and suggestions are made for future work in electro-optic and magneto-optic materials research.