As a result of the large area and great thickness of gas-bearing reservoirs in the Greater Green River basin, many of our investigations have focused on single wells or small areas containing several wells where a large amount of data is available, The investigations include structure, stratigraphy, petrography, x-ray mineralogy, source-rock evaluation, formation pressure and temperature, borehole geophysics, thermal maturity mapping, fission-trace age dating, fluid inclusion thermometry, and isotopic geochemistry. The objectives of these focused investigations are to provide geologic models that can be compared and utilized in tight gas-bearing sequences elsewhere. The purpose of this report is to summarize the tight gas reservoir research activity of USGS geoscientists during FY 88. During the reporting period, most of our efforts were focused on the assessment of gas resources in low-permeability sandstone reservoirs in the Greater Green River basin. Other significant activities included a reservoir study of the Upper Cretaceous Almond Formation in the Greater Green River basin, a fracture study of Cretaceous and Tertiary outcrops in the Washakie basin, and a stratigraphic study of lower Tertiary rocks in the Washakie basin and Rock Springs uplift. 58 refs., 9 figs., 5 tabs.