As the 12th in a series of interim reports prepared for the United States Congress on the metric system, this study was authorized by law to reduce uncertainties concerning the issue of converting to metrication and to provide a better basis upon which the Congress may evaluate and resolve it. The testimony of over 230 nationally representative groups is summarized, supplemented by information from experts in the areas of consumer activity and education. Over 700 trade associations, labor unions, professional societies, and other groups were invited to submit their opinions and cost-benefit estimates concerning a possible future conversion to the metric system. The organizational summaries are grouped into seven categories: (1) labor, (2) consumer affairs, (3) education, (4) construction, (5) engineering-related industry, (6) consumer-related industry, and (7) natural resources, transportation, health, small business, and others. The advantages and disadvantages associated with conversion include international standardization, consumer and industrial retraining and education, changing to new tools, and cost. However, 112 of these groups feel that a changeover is inevitable and desirable, although the complexity of the construction industry would require special planning. A majority of these groups favor a nationally coordinated program with some governmental assistance. (AG)