In this paper, we give a little background into the work of ISO/TC172/SC1/WG1, the ISO subcommittee that is writing standards for the environmental testing of optics and optical instruments. By environmental test standards, we mean standards that outline what sort of climatic variations and conditions of use optical instruments must survive and still operate within given performance specifications. The scope of the standards this subcommittee is writing is then described followed by a thorough description of the general content of the 2 standards that are nearing completion. Finally, we discuss the applicability of these standards and how they may affect optics and optical systems that are intended for sale in international markets. We also discuss briefly the relationship of these ISO standards to MIL-STD-810E, Environmental Test Methods and Engineering Guidelines, the U.S. Military standard.