In an attempt to assess the national impact of anti-war protest, 15 major anti-Vietnam demonstrations occurring in the United States from 1965 through 1971 were analyzed for their effects upon Gallup public opinion survey data, American troop strength, and American munitions expenditures. While weak and short-term counterproductive effects appeared for two opinion indicators, an equally likely conclusion is that the demonstrations had little or no lasting impact whatsoever. The possible reasons for this finding, and its social implications, are discussed.