This report, by a panel established by a complex of associations around the National Academy of Sciences, is the best on the subject to have been published in the 40 years that the United States has exercised controls on exports that might add to Soviet power. It includes interesting, detailed accounts of missions to other countries. Existing practices and some of the efforts of the Defense Department to add to restrictions are severely criticized. The conclusions are to keep controls because they do affect the U.S.S.R., but to accord greater importance to "maintaining U.S. technological strength, economic vitality, and allied unity." The findings depend heavily on tightening multilateral export controls, and this may be the Achilles' heel of the recommendations.