Abstract: This dissertation investigates the development and use of design guidelines employed to direct the outcome of environmentally sensitive, high performance buildings (also referred to as green, or sustainable design) in contemporary building practice. The emerging significance of design guidelines is evidenced by the extent of recent directives centering on environmental health and made available at the national, state, and local levels for manufacturing, design, and development. Attention is given to the U.S. Green Building Council's ‘ Leadership in Energy acid Environmental Design’ [LEED] guideline and rating system, considered as the current default authority for green building design in the United States. The study explores the use of LEED at the formative time of the document's development through a case study of professional practice. The study reveals how practitioners integrate guideline criteria into design and building practice, being both bound by, and challenging the bounds of, the document's criteria. The study is approached from a perspective of structure and agency in organizational practice. The objective is to explore how the recurrent and voluntary adoption of socially constructed standards (norms, customs, or guidelines such as LEED) results in a form of institutionalized practice. Because a single case study lacks a comparative basis, the study findings are viewed in light of previous scholarly research on comparative architectural practices including traditional design and client-situated. As the case study building was awarded the highest certification from the U.S. Green Building Council, representing excellence in environmental design, the development processes employed by a multi-disciplinary team are also compared with excellence in architectural practice as previously defined in architectural research. The results of the study suggest that the use of LEED challenges conventional architectural practice while simultaneously preserving the practice core. Conversely, architectural practice challenges the bounds of the guideline document and sheds light on the social processes of developing building standards. Change in professional practice, when it does occur, is subject to the logics held by practitioners, the extent of shared schemas, and an adopted view of practice as a goal directed systems approach. Suggestions are made as to best practices for guideline use, as well as for future strategies in architectural education.