The INGAA Foundation retained Christensen Associates in May 1990 to study the indexing of interstate gas transportation rates. The eight-month project has included a number of tasks. First, we developed a statement of the public policy arguments favoring gas transport rate indexation. We next identified the major options in the design of a rate adjustment index. The third task was to develop and calculate supporting indexes of industry input price and productivity trends. We then calculated a representative rate adjustment index. This is the final report on our research.