Self-assessment (SA), as an activity for reflecting on one's own performance and abilities (Black & Wiliam, 1998), has been a topic of interest to educators over the years. Among second language (L2) educators, SA began growing in popularity in the 1970s and 1980s, when L2 educators' focus shifted from analyzing linguistic systems to examining how learners learn a language. Many can-do statements and SA descriptors have been developed for L2 language learning, including SA grids aligned with the Common European Framework of Reference (CEFR, Council of Europe, 2022) and can-do statements prepared by the American Council on the Teaching of Foreign Language (ACTFL) in collaboration with the National Council of State Supervisors for Languages (NCSSFL) (ACTFL, n.d.). Textbooks and other L2 learning materials, including online apps, often contain SA items. SA can be used in conjunction with other assessments, such as traditional objective assessments, peer assessments, and portfolios. Teachers are often encouraged to incorporate SA into their curricula as part of the promotion of constructivist approaches to education, which have been particularly popular since the late 1980s (e.g., Nunan, 1988; Tarone & Yule, 1989); SA resonates well with modern learning theories such as learner-centered education, self-regulated learning, and autonomous learning (Butler, in press).