This chapter examines the vastly different approaches in claim construction and specification drafting between the two most important patent jurisdictions, the United States and Germany. Despite the differences in approaches, the same set of claims and description of invention is used in an international application to obtain patents in these jurisdictions. The claim construction rule under the US case law discourages patentees from discussing their inventions, which would make it difficult for German courts to engage in claim construction. This chapter discusses the inherently indeterminate nature of claim wording and reviews US and German case law illustrating the fundamental principles and different sources used for claim construction, in particular specification. It also examines US commentators’ reform proposals and suggests changes to the U.S. case law through implementing the proposition formulated from German experiences.