The book focuses on boredom, a construct that has been explored in educational psychology but has received only scant attention from second language acquisition researchers. Although recent years have seen a growing interest in positive emotions in second or foreign language learning and teaching, negative emotions are always present in the classroom and they deserve to be investigated in their own right. The theoretical part provides an overview of the construct of boredom (e.g., definitions, types, empirical studies in the L2 classroom). The empirical part reports the findings of an empirical study which aimed to examine the changes in the levels of boredom experienced by a group of English majors in English classes and identify the factors accounting for such changes. The book closes with a discussion of directions for further research as well as some pedagogic implications.