Previous ERP implementation studies focused primarily on single-site and domestic implementations. The issue of ERP implementation at facilities across nations has been seldom discussed, although industry has indicated such a need. This exploratory study investigates the relationships between national differences and multi-national ERP implementation. Using case research that involves direct observation and systematic interview at four US and Taiwanese manufacturing firms, this study investigates what and how national differences affect implementation practices across nations. The results suggest that language, culture, politics, government regulations, management style, time zone, and labour skills impact several ERP implementation practices. Understanding such effects will enable companies to be more proactive in planning for multinational ERP implementation. Managerial implications of the findings and future research issues are discussed.