We can describe as well as explain the *symmetries as well as the *gaps in inventories of vowels and consonants. Symmetries are the language-speciŪc results of general human limitations on the acquisition of perceptual categorization and motor skills. Gaps are the results of local hierarchies of articulatory effort, perceptual contrast, and perceptual confusion. There is no need to posit a dedicated inventory grammar: inventories are the automatic result of the constraints and their rankings in the production grammar.