The development of the Space Shuttle Orbiter in the early 1970s marked the first time that a fracture mechanics approach was taken to the design of the window systems of a manned space craft. Earlier vehicles were never subjected to repeated launch and re-entry and therefore fatigue or slow crack growth were not major concerns. The design and proof test methodology evolved at that time continues to be applied in the development of the window systems for the Space Station Freedom. A combination of fixed abrasive grinding, lapping, and chemical machining is employed on the fused silica window panes to insure that sub- surface damage is carefully controlled and minimized. All panes are proof tested under controlled atmospheric conditions which preclude crack growth during the test. This paper also covers some of the history of space craft window design, the rationale for the material choices as well as a review of the finishing and test methods employed.