This thesis addresses the acoustic realization of tone in the Lower dialect of the Koyukon language. The Lower dialect is the only one of the three Koyukon dialects attested to have tone. Its exact nature, however, remains unclear. This study seeks to corroborate previous attestations of low tone in Lower Koyukon by providing acoustic evidence of its realization. Therefore, there are three primary objectives: a) to determine how tone is produced in Lower Koyukon with respect to pitch; b) to examine any interactions between tone and potential pitch-altering phenomena; and c) to determine the realization of creaky phonation during tone production, if such exists. All of the data for this study was gathered from a single consultant, a fluent Lower Koyukon speaker. Three elicitation strategies were employed. First, a game of bingo was developed from a list of words predicted to carry a tonal syllable. Second, the consultant was asked to teach the researcher how to pronounce a series of short phrases and sentences that contained a word with a tonal syllable. Finally, the researcher selected a story written in Koyukon for the consultant to read aloud. During the analytical process, each word predicted to carry tone was compared to both a control set of non-tonal words and a set of words that may or may not carry tone. The only statistically significant difference was that the set of tokens predicted to carry tone had higher measures of creak than the control set. As creaky voice is inherently linked to tone production, this finding supports previous attestations of tone. However, both quantitative and qualitative methods were employed for this study, and several examples are cited which show both that there is a significant pitch change on syllables predicted to carry tone. Moreover, it appears that that this pitch rises. The implications of this study are therefore that tone is present in modern Lower Koyukon, and that this tone may by high, rather than low, as has been previously claimed.