The report Preface: In an article by Thomas T. Williams and Robert B. Glasgow in the American Journal of Agricultural Economics, December 1968, a technique developed by Mr. Glasgow for estimating underemployment was presented and applied to 92 State economic areas. This report explains the technique used and includes underemployment estimates for all counties in the United States and a summary analysis of the Nation as a whole. Data from the 1960 Census of Population were used, the most recent available for this particular technique. These estimates provide comparisons of labor force utilization among counties and are useful as a basis for current economic appraisals and policy recommendations. They are being published to satisfy the demand for this type of economic indicator.