In 2007, a group of researchers proposed the term "grit" to describe a trait in people who have the diligence and endurance to keep working for a goal in spite of various setbacks, such as extended lengths of time to reach the goal, changing interests, or other problems encountered along the way (Duckworth et al. 2007). According to these researchers, accomplished and successful people throughout history have had this grit trait that has set them apart from other people. Currently, many educators feel that the research on grit points to an innovative way to produce higher-achieving students. If the claims about grit are valid, then developing students' grit is as important as developing their cognitive strategies and skills. Furthermore, examining grit in language learning provides valuable insights into why some second- or foreign-language learners are more successful than others. The purpose of this article is to investigate grit: what it is; how it has been measured; how it connects with research in the second- and foreign-language field; and how it can be applied and promoted in language-learning classrooms.