This study investigated the perceptual dimensions of tone in Vietnamese and the effect of dialect experience on listener's prelinguistic perception of tone. While Northern Vietnamese tones are cued by a combination of pitch and voice quality, Southern Vietnamese tones are purely pitch based. 30 listeners from two Vietnamese dialects (10 Northern, 20 Southern) participated in a speeded AX discrimination task using northern stimuli. The resulting reaction times were used to compute an INDSCAL multidimensional scaling solution and were submitted to hierarchical clustering analysis. While the analysis revealed a similar three-dimensional perceptual space structure for both listener groups, corresponding roughly to f(0) offset, voice quality, and contour type, the relative salience of these dimensions varied by dialect: Southern listeners were more likely to confuse tones produced with nonmodal voice quality, whereas Northern listeners found tones with similar pitch excursions to be more confusable. The results of hierarchical clustering of the stimuli further support an analysis where low-level perceptual similarity is influenced by primary dialect experience.