Background: Vocabulary frequency results have been reported to design and support augmentative and alternative communication (AAC) interventions. A few studies exist for adult speakers and for other natural languages. With the increasing demand on AAC treatment for Korean adults, identification of high-frequency or core vocabulary (CV) becomes essential. Aims: The overall objective was to identify the frequency and commonality of spoken Korean words that occurred in spontaneous conversations for the development of AAC interventions. The specific aims were: (1) to generate a Korean CV list based on the conversations of Korean adults; (2) to address the characteristics of the identified words; and (3) to determine whether a quantitative data analysis procedure, based on a grouped frequency distribution, would support identifying high- and low-frequency words. Methods & Procedures: Language samples were collected from 12 native Korean-speaking adults during conversation. CV words were identified based on a grouped frequency distribution analysis and a word commonality analysis. Outcomes & Results: Results established a Korean CV list of 219 words with high frequency and commonality accounting for 60.82% of the total sample. Analysis of word types showed a wide range of particles and verb endings in the CV list. Finally, a distinct distribution pattern was identified from a frequency of 0.2% to support high-frequency word selection. Conclusions & Implications: The CV list and consideration of the linguistic characteristics of Korean are expected to be used to develop Korean AAC interventions. The grouped frequency distribution revealed a robust method to distinguish high-frequency words and to improve AAC vocabulary selection and organization.