This chapter considers the literature on language learning anxiety in an effort to clarify the relationship between anxiety and second language learning. It will first argue that language anxiety is a specific anxiety — rather than a trait anxiety — and discuss how this conceptualization has helped clarify the research literature. After Horwitz, Horwitz, and Cope (1986) proposed that a specific anxiety construct which they called Foreign Language Anxiety was responsible for students’ uncomfortable experiences in language classes and offered an instrument, the Foreign Language Classroom Anxiety Scale (FLCAS), to measure this anxiety, findings concerning anxiety and language achievement have been relatively uniform, indicating a consistent moderate negative relationship between anxiety and achievement. However, some researchers (Sparks and Ganschow and their colleagues) have suggested that poor language learning is a cause rather than a result of language anxiety. This review concludes that anxiety is indeed a cause of poor language learning in some individuals and discusses possible sources of this anxiety, including difficulty in authentic self-presentation and various language teaching practices. In addition, it reports on new trends in language anxiety research that attempt to identify aspects of language learning (e.g., reading anxiety or writing anxiety) which provoke anxiety for some individuals.