Vowels are universal in human languages and have long been categorized in feature systems. However, the feature systems are based on introspection and include a notion of ‘‘height’’ or ‘‘closeness,’’ that is not anatomically straightforward. From x-ray and other imaging data, the important aspects seem to be palatal, velar, and pharyngeal closures, with secondary effects of lip rounding. Describing vowels in terms of location of constriction makes some assimilation patterns more direct, as with palatal vowels (e.g., /i/) conditioning palatal fricatives. Vowels can also be described as intrinsically slower than consonants, which allows for a more straightforward description of their timing relationships, and a possible explanation for the crosslinguistic preference for CV syllables. The use of fricatives for syllabic nuclei is common in languages and derives easily from a narrowing of the constriction to the point at which frication is generated. More and less vowel-like patterns in consonants have also been noted, such as in coarticulation of laterals and rhotics. Gesture-based systems have difficulty describing some phonological patterns (e.g., vowel lowering). The status of schwa, which seems to lack a constriction, is unclear. With two competing systems having different advantages, work directly comparing the approaches is needed within speech science.