English echo questions present numerous challenges to the analysis of interrogatives, including (a) simple wh-in-situ (You saw who?); (b) apparent Superiority violations (What did who see?); (c) apparent verb movement without wh-movement (Has Mary seen what?); and (d) requisite wide scope only for echo-question-introduced wh-phrases (underlined in these examples—only who in What did who see? is being asked about). Such apparently contrary features may be explained in terms of independently necessary scope assignment mechanisms and a complementizer that subordinates the utterance being echoed and “freezes” its CP structure. No norms of question formation are violated.