Book excerpt: This book discusses how UNIDROIT principles are viewed and interpreted in different countries, presenting various perspectives and practical lessons learned. It also offers a detailed analysis of the use of the UNIDROIT principles to interpret and supplement domestic contract law. Written by experts in the field, it provides insights into how the principles are being used and applied in their respective countries. The findings are also summarized in a General Report that was presented at the 20th IACL General Congress in Fukuoka, Japan.