Lee, Sang-oh. 1998. Auxiliary Inversion of Wh-interrogative Questions and Checking. Studies in Modern Grammatical Theories 12, 125-139. The purpose of this paper is to discuss the auxiliary inversion and its checking relation of wh-interrogative questions in English in the light of various assumptions made by minimalist theory in linguistics. Following the basic hypothesis that the auxiliary inversion in wh-questions depends on the strength of the head C of CP, the requirement that the C of CP be filled by some element fulfills the operation of auxiliary inversion by being attracted (adjoined) to the question affix(Q). Furthermore, the data drawn from Belfast English and the successive cyclic A´-movement of wh-expressions are used to discuss the function of the specifiers of CP containing overt or null elements, which play important roles in explaining the auxiliary inversion in wh-interrogative questions. The constructions such as subject questions, non-interrogative embedded clauses, and non-interrogative questions are also discussed for the aim of suggestion that only the head feature of C of CP containing overt wh-specifiers is strong enough to attract the auxiliary into the question affix.