This chapter focuses on the measurement of foreign language anxiety (FLA). It begins by clarifying the construct of FLA and establishing it as a situation-specific form of anxiety within the context of foreign language (FL) learning. The chapter then offers a detailed and critical review of major FLA instruments, including general FLA scales, skill-specific anxiety measures, language-specific scales, instruments developed for heritage language learners, and FL test anxiety scales. A standardized seven-stage procedure for scale development and validation is outlined and illustrated through two exemplar empirical studies. The chapter concludes by discussing the practical applications of these instruments for identifying anxious learners and highlighting areas in which new or improved FLA measures are still needed.