Information about the lexical capacity of the speakers of a specific language is indispensible for empirical and experimental studies on the human behavior of using speech as a communicative means. Unlike the increasing number of gigantic text- or web-based corpora that have been developed in recent decades, publicly distributed spoken resources, espcially conversations, are few in number. This article studies the lexical coverage of a corpus of Taiwan Mandarin conversations recorded in three speaking scenarios. A wordlist based on this corpus has been prepared and provides information about frequency counts of words and parts of speech processed by an automatic system. Manual post-editing of the results was performed to ensure the usability and reliability of the wordlist. Syllable information was derived by automatically converting the Chinese characters to a conventional romanization scheme, followed by manual correction of conversion errors and disambiguiation of homographs. As a result, the wordlist contains 405,435 ordinary words and 57,696 instances of discourse particles, markers, fillers, and feedback words. Lexical coverage in Taiwan Mandarin conversation is revealed and is compared with a balanced corpus of texts in terms of words, syllables, and word categories.