This thesis investigates the relationship between the phonological distribution of Cw combinations, and the acoustic/perceptual distinctiveness between syllables with plain C onsets and with Cw combination onsets. Distributional asymmetries of Cw combinations discussed in this thesis include the avoidance of Cw combinations in the labial consonant context and before rounded or back vowels, and the preference for contrastive labialization on velar consonants. Following the claim that the phonetic salience of phonological contrasts should be taken into account in the explanation of typologically common co-occurrence restrictions (Kawasaki 1982, Flemming 1995, et seq.), I focus on showing that the salience of the contrast between CV and CwV syllables is a major factor in the asymmetric distribution of Cw combinations, with supporting evidence from acoustic and perception experiments. The results of a study on the C-Cw comparison in Korean and Spanish show that the acoustic difference between plain C and Cw combination is weaker in contexts where Cw combinations are avoided. In addition, cross-linguistic comparison reveals that the phonetic status of the /w/ component--a glide consonant or a secondary labialization--affects the acoustic distinctiveness of a Cw combination relative to the plain C counterpart. Perception experiment results confirm that the degree of acoustic distinctiveness between CV and CwV syllables in different consonant and vowel contexts is reflected in the strength of perceptual cues to the contrast. Based on the findings from the experimental studies, I propose an analysis of the Cw asymmetries within the Dispersion Theory of Contrast (Flemming 1995, et seq.). The asymmetric distribution of Cw combinations emerges because the contrast between CV and CwV is allowed only when they are separated by sufficient perceptual distance. Optimality-Theoretic interaction between such requirements on perceptual distance (minimal distance constraints) and constraints governing the preservation of contrast gives rise to the asymmetries in the distribution of Cw combinations observed in languages like Korean, Mandarin, Cantonese and Dan. I compare the current analysis with an alternative identity avoidance (OCP) analysis, and argue that the former is superior in terms of both descriptive and explanatory adequacies. I also show the parallel between the distributional asymmetries of Cw and Cj combinations, and extend the Dispersion-Theoretic analysis to the Cj distribution for languages like Ukrainian. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]