This paper investigated how dialectal variations can influence the realization of tonal register and declination pattern in Taiwan Mandarin. Twelve speakers, six from the Northern dialect (standard) and six from the Central dialect (nonstandard), were recruited for a reading task. Target syllables of Tone 1 (T1) were embedded in a carrier sentence in three different sentential positions, initial, medial, and final. The dependent measure was the F0 maximum of the target syllables. Results showed that the Northern dialect had higher T1 register than the Central dialect, with the effect being more prominent in males than females. The magnitude of declination was also a function of gender and dialect. Central male speakers produced milder declination slopes than their Northern counterparts while Central female speakers tended to have steeper slopes instead by raising the initial starting pitch, indicating that in the Central dialect, female speakers were more aware of their vernacular speech status compared to male speakers and tended to hypercorrect their nonstandard accent by using a larger pitch range.