Jeong-sil Song. 1997. Non-Argument XPs. Studies in Modern Grammatical Theories 10: 1-20. The main purpose of this study is to argue for the following points concerning English non-argument XPs. First, they all have the structure of XP in which one and only one argument position is not saturated. Second, they are all adjoined to an X`, modifying the X`. Third, some of them also function as a secondary predicate of the DP in the Spec of the XP. This study adopts the hypotheses of XP-internal Subject, Split Infl, and Split VP with some modification.