This is the first of several reports on the Arizona Unemployment Insurance Benefit Adequacy Study. Initiated in July 1975, the investigation constitutes the most comprehensive examination yet undertaken of the adequacy of the UI weekly benefit amount. The entire study, including an analysis of the post exhaustion experiences of those in the study group who exhausted their UI benefits, is scheduled for completion in January 1979. Although this report provides a brief overview of historical developments in benefit adequacy research, emphasis is placed on the formulation and results of the empirical analysis conducted in the first phase of this study. The analysis at this stage emphasizes comparisons between weekly UI benefit amounts received by beneficiaries while unemployed and the standard of living (as measured by expenditure levels) maintained by their households prior to the spell of unemployment. Further analysis of benefit adequacy, including investigation of the types of adjustments undertaken by beneficiaries during the period of unemployment or following benefit exhaustion, will be undertaken. This analysis will be presented in subsequent reports.