“With whom did you go” is grammatically correct because “whom” is the correct objective-case pronoun. But at least in America, 90% of people will say “Who did you go with” even though the pronoun is technically incorrect. The grammatically correct way sounds old-fashioned, formal, or like someone is trying to sound fancy. My advice: in casual conversation among friends, “who did you go with” is a good choice (at least in America). In more formal settings or with persons who care a lot about “proper” grammar, use “With whom did you go.”

Hi Elena. 'Who did you go with?' is more natural, but it is incorrect because whom is the correct form to use when it is an object, and also, it is grammatically incorrect to end a sentence with a participle (this is called a 'dangling participle'.) 'With whom did you go?' is technically more correct; however, no one speaks like that because it's extremely formal, so in casual conversation, use 'who did you go with?' and save the other question for more formal settings.

Both are understood and correct. With whom did you go? ( Chiefly British ) Who did you go with? ( Chiefly American )

Whom is the correct form

Never in my whole life have I ever said: "With whom did you go?" Perhaps they say that in England. I don't know. I agree with everyone else. It sounds old fashioned and extremely formal. Also I want to add that it is perfectly acceptable to end a sentence with a preposition. The "rule" against this is just a myth that I believe originates from when French was the prominate language in England and English speakers wanted to be more French. In French you do not end a sentence with a preposition.