Kormos and Wilby provide an overview of task motivation from both a theoretical and empirical perspective. The chapter begins by defining task motivation in second language acquisition research as being composed of both trait- and state-like characteristics. Following the general definition, six main theories of task motivation from educational psychology are summarized, namely, achievement goals, self-efficacy, expectancy value, intrinsic motivation, flow, and interest. The second half of the chapter reviews studies of task motivation in second language acquisition research and discusses the relationships between task motivation and task characteristics, task performance, social factors, and changes in task motivation over time. In concluding the chapter, Kormos and Wilby make suggestions for future research in this relatively under-researched area of motivation.