This thesis gives a phonological representation of the Mandarin Chinese Neutral tone (T0) within disyllabic sequences using Optimality Theory, morphology, and semantic structure. This thesis states that T0 in Mandarin is caused by a phenomenon called Loss of Coda Licensing, which states that codas of non-head syllables that have a low semantic influence on the disyllabic sequence lose their ability to associate with a tone, causing the syllable to become a T0 syllable. To experience Loss of Coda Licensing, non-head syllables are evaluated for their semantic influence and subsequently placed into two categories: high influence and low influence. Low-influence syllables are then placed into one of five categories, with each category containing a phonological constraint that affects the syllable's coda to license a tone. This thesis utilizes Optimality Theory to posit a phonological representation that shows, like Mandarin's four lexical tones, that T0 is also a tone, even if it is shorter in length than the lexical tones. This thesis's phonological representation shows that a T0's Tone differs from that of a lexical tone because T0's Tone depends on the preceding lexical syllable's coda tone. The implications of this thesis are that tonal realization within disyllabic sequences depends on semantic contributions, that T0 syllables contain a coda that cannot license a tone, and that non-head syllables can be categorized within Chinese.