Wallpaper is a significant decorative finish of late nineteenth century interiors. Determining the appropriate approach for treatment in situ, execution of a custom reproduction, or the selection of an appropriate reproduction for a "period look" requires extensive research by an interior designer. The integrity of the historic interior can be lost or compromised during the restoration or rehabilitation process if it is based on misguided decisions. The conservation principles established in the Venice Charter and the criteria or guidelines established in the Secretary of the Interior's Standards for Rehabilitation must be considered before a plan is implemented.The emphasis of this thesis will be establishing a methodology which addresses the design issues confronting interior designers with regard to historic wallpaper in the context of restoration and rehabilitation or adaptive use projects. The period of 1870-1900 reflects a major change inexhibitions have examined aspects of this complex period and it style and the peak period for production and use of American wallpaper. This is the most misunderstood period with regard to wallpaper because the rejection of wallpaper by the modern movement lingers today. In the past decade, four major museum is now being viewed as a critical cultural and artistic watershed.Through research, an appreciation of the various patterns and colorways will be developed. The technological innovations which affected the quality and quantity of wallpaper will also be examined. Documentation of wallpaper for this period will also include reference collections, interior photographs taken during the period, and examination of original sources written during or preceding the period. A survey of what documented reproductions are available on the market today and which are appropriate for interiors of American buildings constructed in the decades 18701900 will be reviewed. Books have been written on the subject of wallpaper, but a single reference does not exist with the information and guidelines needed by designers working on restoration and rehabilitation projects.The selected case studies examine the restoration and rehabilitation approaches to wallpaper. Conclusions were drawn from the diverse projects to reveal the broad range of appropriate treatments or solutions in the context of projects and issues. / Department of Architecture