With the recognition of the historic and artistic merit of American stained glass, the conservation community is faced with difficult problems of its conservation. The bulk of American stained glass is about 100 years old. It is beginning to show signs of unique and serious deterioration. There is little research into the causes or into the conservation methods applicable to these conditions. It is time to look at these issues, to research the conservation of this stained glass, and to train U.S. craftsmen and conservators to deal with these problems, before losing these treasures. See also AATA 21-870.