The National Minimum Drinking-Age Act of 1984 was hailed by some observers as a welcome and appropriate exercise of federal power. However, the act also constituted an invasion of states' rights. The act stipulates a minimum legal age of 21 for the purchase or public possession of any alcoholic beverage, and incorporates sanctions against states whose laws are not in compliance. This article evaluates the constitutional bases for federal intergovernmental regulation in a policy area dominated by states since the repeal of prohibition in 1933 by the Twenty-First Amendment. It also considers the effectiveness of policies designed to prevent alcohol-related highway deaths, and the relative merits of federal incentives or penalties to induce desired behavior by the states. The article concludes that the states, for which the Reagan administration's early theme of decentralization was so promising, may continue to find both their federal funds and individual autonomy seriously compromised in the foreseeable future.