This paper focuses on the good faith principle in contracts and international trade. The paper examines the description of the good faith principle in common law and civil law jurisdictions and various approaches to Article 7 (1) of the Vienna Sales Convention that requires the need to promote the observance of good faith in international trade. The paper reviews the drafting history of the Article, interpretation of good faith under common law and civil law, the UNIDROIT and Uniform Commercial Code. The paper concludes by proposing a uniform understanding of the Convention’s good faith principle by clarifying its function, its conceptual boundaries, and by defining the scope of other related obligations.