Environmental sustainability has become one of the most visible considerations for today's built environment. Over the past thirty years, there has been an increasing focus on developing and implementing sustainability principles as a means to promote environmental stewardship and the protection of life and natural resources. While we tend to think of sustainability design as a fairly recent phenomenon, is it really? It is doubtful that the architects of historic American buildings ever heard the terms "sustainable design" or "going green," however, many of their designs reflect inherent sustainability principles. The premise of this paper is that sustainability principles have been used throughout American architecture and an important role of historic preservation is to identify and communicate these principles. The goal of this paper is to document and provide a catalogue of some of the more innovative historic approaches to achieving environmental sustainability in American architecture.