Using native language for research discussion in an English-speaking country My university is in an English-speaking country, hence most of people use English for communication. However, it is possible to have a supervisor and her student that are from the same country, which is not an English-speaking country.

When that happens, is it acceptable if they use their native language in discussion regarding the PhD research while at school?
Yes. I see this all the time in my school. Although some professors avoid doing so. I believe it can loosen some faculty/student boundaries. Also, it is advisable to use English language when accompanied by other students/faculty who can not speak that native language.