This paper reviews previous research in second language (L2) complaint realization. Complaint realization refers to a type of speech act in order to express the speaker’s displeasure or dissatisfaction when s/he thinks that the interlocutor’s act is unacceptable. Because it is a type of face-threatening act including both negative and positive face, appropriate complaint realization is difficult to achieve for L2 learners.

Research in this field has so far investigated L2 learners’ production (their strategy use and directness of speech) when making complaints. Previous studies have shown that L2 learners’ strategy use plays a crucial role in complaint realization, and their complaint realization tends to be more direct compared to that of native speakers.

More recent research has focused on L2 learners’ perceptions about complaints in the L2. However, compared to traditional production-based studies, the number of perception studies is limited, particularly in L2 complaint research. Therefore, more future research is expected to advance our understanding in this field.