I don’t know about Carleton, but can answer your questions for Grinnell. Grinnell is incredibly accepting of all students and has a large percentage of international students. My son lived in substance free housing for 1st 3 years, he choose a single senior year on side of campus with substance free housing, but not a substance free dorm. They are very popular choices. He describes the campus as 1/3 drinkers, 1/3 drugs and 1/3 substance free. Whatever your choice, you will find your people and not be judged. Again, Grinnell is Iowa nice and accepting.