The purpose of this study is to find out the characteristics of the office space as designed by Gwathemy Siegel and thereby to understand the current trend of interior design of working space in the United States. Unlike most architects, Gwathmey Siegel have extended themselves into interior designing of over twenty offices including law firms, financial institutions and design firms and have successfully won reputation as interior designers. They have distinguished themselves by their ability to turn up and take advantage of the possbility of shaping in a given structure. Their liberal use of fixed furniture and architectural lighting , in addition to ceilings and walls , set them apart from others in the field . The major design elements and principles of Gwathmey Siegel include, among others : 1) Curved and slanted walls on the floor plans endow the office space with forms. Fixed furniture and architectural lighting frequently serve as from -creating elements. 2) The openness of the reception and waiting areas and the irregularity of the corridor walls add a sense of variety in the office. 3) In terms of color and materials, subtle changes of texture and value and the various patterns of joint lines further enrich the space. 4) The principle of symmetry , rough or partial , as applied in the layout of rooms and furniture creates a sense of balance in the space.