The consonant/vowel distinction is surprisingly poorly understood. Consonants and vowels are often distinguished either by constriction degree or syllable position, but neither of these is exceptionless. This dissertation presents a new account of the distinction: the Domain Prioritization Hypothesis. The underlying difference between consonants and vowels is that consonants prioritize the articulatory domain and vowels prioritize the acoustic domain. These domains are realized in the cognitive system largely through feedback processes. Evidence in support of this hypothesis comes from cross-linguistic and experimental data on glides, the most vowel-like consonants. The experimental results show differential patterns in the variances of articulatory and acoustic measurements and in responses to altered auditory feedback. Domain prioritization is formalized in the framework of Articulatory Phonology and Task Dynamics by expanding the possible functional coordinates for speech task goals to allow such goals to be represented in all sensory modalities: consonantal gestures aim to achieve targets defined in a functional space that is an abstraction of the vocal tract, but the appropriate functional space for vowel targets is instead an abstraction of acoustic formants. This approach has potential explanatory power with regard to a variety of phenomena related to the C/V distinction, including syllable structure and complex segments.