Language use and communicative behaviors are important indicators of sojourners' adjustment. The current research was conducted to understand international students' communication behavior on Facebook during their adjustment period in the US and its relationship to the students' acculturative attitude (identification with heritage and mainstream culture), current psychological adjustment level, socio-cultural adaptation level, and target audience on Facebook. Two main theories provided the theoretical framework of the study: Giles' communication accommodation theory (1973) and Berry's acculturation model (1984). Snowball and convenience samples were used to recruit 178 international students from different universities across the US. A mixed approach of online survey and content analysis was used to test the hypotheses and research questions. The results showed that during the stay in the US, international students accommodate their language and topic choice towards their American peers on Facebook. Particularly, it was found that language accommodation levels increase as the students' length of stay in the US increases. The results also demonstrate that international students use Facebook mainly to communicate with friends who reside in the US. When students had higher levels of mainstream identification, they were likely to target American friends as their audience on Facebook and thus have more language and topic accommodation. Additionally, acculturation attitude (heritage and mainstream identification) predicted the students' language accommodation level. Lastly, the study showed that there is a positive relationship between language accommodation and sociocultural adjustment. The findings of the study not only expand the scope of communication accommodation theory and acculturation model, but also enhance understanding of international students' online communication patterns, their purposes, and practical consequences upon their adjustment in the US. This is important because it can be useful in finding ways to improve the students' experience in the US.