Linguists researching the sounds of languages do not just study lists of sounds but seek to discover generalizations about sound patterns by grouping them into categories. They study the common properties of each category and identify what distinguishes one category from another. Vowel patterns, for instance, are analysed and compared across languages to identify phonological similarities and differences. This original account of vowel patterns in language brings a wealth of cross-linguistic material to the study of vowel systems and offers new theoretical insights. Informed by research in speech perception and production, it addresses the fundamental question of how the relative prominence of word position influences vowel processes and distributions. The book combines a cross-linguistic focus with detailed case studies. Descriptions and analyses are provided for vowel patterns in over 25 languages from around the world, with particular emphasis on minor Romance languages and on the diachronic development of the German umlaut.