漢語中有許多表達處所與方位的「方位詞」，但文獻中不僅缺乏明確的定義，其所屬詞類與其詞態屬性也多有爭議。本文的目的是對以上議題提出系統性的分析。我們首先利用介詞「在」要求處所論元的特性來界定方位詞，並指出方位詞在語意上的完整指稱需依賴其先行詞。處所詞倒置的句法構式則提供了進一步驗證方位詞的方法。我們接著檢視方位詞詞態屬性的三種可能：（自由）詞、附著語素、詞綴。以連接詞、簡答與插入「的」等三項測試所得到的結果是：單音節方位詞主要是附著語素，而非詞綴，僅在有限的環境中是詞；雙音節與多音節方位詞則都是詞。而在詞類的歸屬上，本文論證所得的結論是方位詞均有名詞的特徵，並非後置詞，也不應視為獨特的詞類。

In Chinese linguistics, “localizers” is an accepted term referring to a set of morphemes indicating the relative location or place of an object; however, not only is a precise definition not available in related literature, but the precise syntactic category and morphological status of localizers are both controversial. The purpose of this paper is to examine these issues systematically and offer a comprehensive and insightful account. We first define a localizer as the locative argument of preposition zai's 在 “at,” whose reference relies on a preceding nominal antecedent. The locative inversion construction then serves as a further test for localizers. As for their morphological status, we examine the three possibilities: word, clitic, and affix. The results of three different tests, namely conjunction, short answer, and de 的 insertion, show that localizers with two or more syllables are all words, while monosyllabic localizers are in general clitics, except in highly restricted contexts where some may be words. All localizers are nominals, thus being neither postpositions nor another independent syntactic category.