This dissertation explores four Korean discourse markers derived from question words: "mwe" (what), "way" (why), "ettehkey" (how), and "mwusun" (which; what kind of). Most Korean question words have an additional function as indefinite words that refer to a nonspecific referent (Kim, 2000; Yang, 2005). In addition, many of these forms have discourse-pragmatic functions as discourse markers, as well (Kim, 2005; Koo, 2004; Suh, 2007). Corpus analysis shows that "mwe", "way", "ettehkey", and "mwusun" are highly frequent wh-words that are also frequently employed as discourse markers, which carry out various pragmatic functions and have no syntactic role, in naturally occurring spoken conversation in Korean. Research has also shown that discourse markers develop from Korean question words as the outcome of grammaticalization processes (Rhee, 2016). This study takes a diachronic approach to demonstrate that "mwe", "way", "ettehkey", and "mwusun" have gradually developed through grammaticalization processes into discourse markers that express the speaker's modality or index the speaker's intersubjective consideration of the addressee(s). The study also takes a synchronic approach to understand these four discourse markers' functions in contemporary Korean. It applies conversation analysis to spoken data from two sources: the Korean Telephone Conversations Speech Corpus and several recently produced Korean television dramas. The results shed light on the general characteristics and developmental paths of Korean discourse markers that originated as question words and indefinite words from the perspective of grammaticalization and pragmaticalization. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]