This publication was awarded the Jacqueline Ross TOEFL Dissertation Award in 2009. Since its publication in 2001, the Common European Framework of Reference (CEFR) has been the most frequently-cited performance standard in language testing in Europe. To help test providers and users with score interpretation in relation to the CEFR levels, the Council of Europe published the `Manual for relating language examinations to the CEFR'. Even though the linking process set out in the Manual is primarily based on judgements by trained participants, judgement-making in this context remains largely unexplored. The research presented in this book addresses this issue by employing quantitative and qualitative methods. Despite the judges' good understanding of how language ability progresses from lower to higher CEFR levels, it was found that describing test content and examinee performance was not without problems and decision-making was affected by a number of factors that were irrelevant to the judgement task. The results provide a better understanding of judgement-making during the CEFR linking process, which has important implications for examination providers and users of CEFR-aligned test scores.