The Common European Framework of Reference for Languages (CEFR) began to have an influence on language teaching some 20 years ago. However, in spite of the title referring to learning, teaching and assessment of languages, the CEFR has had a far more pronounced impact on language testing than on any other aspect of language learning/teaching. In contrast, this article focuses on the impact of the CEFR on teachers by analysing the beliefs about and perceptions of the CEFR held by a group of Spanish teachers about to take a Masters course module on the CEFR. A 35-item questionnaire was administered to these in-service teachers online to analyse their familiarity with the CEFR, their perceptions of the impact of the CEFR and their knowledge of the contents of the CEFR. The analysis shows that teachers' degree of familiarity with the CEFR as a whole was superficial. They reported a high degree of familiarity with levels of competences, but limited knowledge of changes that the CEFR proposes, despite the fact that they perceived the general impact of the CEFR on syllabi, curricula and methods to be substantial. There are clear implications for teacher education to ensure more thorough understanding of the CEFR.