SAY verbs crosslinguistically have been widely reported to undergo certain grammaticalization processes and to be used as quotative markers, complementizers, evidential markers, and discourse markers. The main purpose of this study is to investigate the grammaticalization of the SAY verb zin in Kavalan, a highly endangered Austronesian language spoken on the eastern coast of Taiwan. It is shown that the Kavalan SAY verb zin has undergone the process of grammaticalization and come to be used as a semicomplementizer and stance marker. It is proposed that zin has undergone two pathways of grammaticalization and that there are two different forces underlying these two pathways. On the one hand, the mechanism of morphosyntactic reanalysis leads zin to be grammaticalized as a semicomplementizer. On the other hand, it is the forces of (inter)subjectification that lead zin to be open to being reinterpreted as a stance marker.