The morphological structure of the nouns in Yupik Eskimo is highly complex. Past attempts at its classification are recapitulated, and a new analysis is proposed within the theoretical framework of generative phonology. The new classification is informative: it reveals the innate structures underlying the various noun types, and also provides insights into historical and dialectal variants of the language. Furthermore, the seven traditional noun classes have been reclassified and simplified into two major types with few minor exceptions. What appears to be a highly complex linguistic structure is revealed as an intrinsically simple system of underlying forms and recurrent phonological processes. (Author/CLK)