Chapter Five, Structure and Reinforcement, from the Stained Glass Association of America's Reference and Technical Manual. We all have a responsibility to our chosen professions and that is to be professional in the manner in which we conduct and practice that calling. There must be a constant effort to expand one's knowledge and skills in the performance of one's work. Towards this end one must always seek improvement and maintain a student curiosity, be open to new ideas, new and different or improved procedures. In this manner we grow and avoid the destructive stagnation of 'knowing it all.' It is important to the survival of our profession, that practitioners and anyone remotely involved in stained glass be aware of approved methods, as well as improvements on traditional procedures which have come to light. To this aim I have dedicated this chapter. However, there can be no chapter, no book, or series of books totally comprehensive in our specialized discipline, for the scope of procedures vary greatly from one studio or practitioner to another as do new procedures and techniques evolve constantly. Opinions may vary as to what is the most important element contributing to the success of a stained glass work. Though undeniably important, as are all the components in the successful production of stained glass, the essential ingredient to its survival is structure and the supplementary support, reinforcement. The emphasis placed on appropriate and adequate reinforcement should not be interpreted to imply that ours is a 'fragile art.' It is not. In the range of materials for creative expression, ours is one of the more durable. Unlike oil painting, watercolor, fresco, tapestry, and sculpture, ours is much less the victim of the ravages of time. Given the condition in which stained glass has usually existed-that of the extremes of nature's exposure on the exterior surface and that of an interior on the other surface combined within a thickness of approximately