To modify foreign policy to suit the post-Cold War era, the United States has proposed the strategy of democratic enlargement, replacing the outdated communist containment. This paper analyzes and assesses the theoretical underpinnings and policy practices of the enlargement strategy. To export democratic systems abroad not only coincides with fundamental American values but also reflects the security concerns of the Clinton administration. The democratic -peace theory, which claims the absence of war between democracies, serves as the rationale for the curity dimension of enlargement policy. We discuss the four pillars to democratic enlargement: 1) strengthening the community of major market democracies; 2) fostering and consolidating new democracies; 3) countering internal and external threats to democracies; and 4) pursuing humanitarian agenda. A combination of tools (economic, diplomatic, political, military, etc.) is necessary to attain the above four goals. The implementation of enlargement strategy, however, has drawn much criticism, on both theoretical and practical grounds. From the theoretical perspective, the causality between democracy and peace remains vague, the definition and operation of relevant variables loom problematic, and the reliability of empirical' evidence awaits improvement. In, practice, the overconfidence in democracy-produced peace, the exaggeration of U.S. ability to transform other countries, the underestimation of other countries' likely response and intolerance of foreign intervention, and the overemphasis on the incompatibility between non -democracies and democracies may all contribute to the defeat of the enlargement strategy.