Abstract: Lexical processing is at the core of written and spoken language. Language users have a remarkable ability to create, produce, and comprehend complex words. Words such as 'undercut' and 'bakery' are composed of units, called morphemes, that recombine in rule-like ways to form other words, such as 'underline' and 'cannery'. However, morphological systems are only partially regular. They are systematic and productive but admit many seemingly irregular forms. Thus, 'bakery' is related to 'bake' and 'cannery' to 'can' but what is the 'groce' in 'grocery'? There is no bread in 'sweetbreads', liver in 'deliver', corn in 'corner' or ginger in 'gingerly'. Such words exhibit only partial regularities in the correspondence between form and meaning. The treatment of these partial regularities has important implications for linguistic and psycholinguistic theories. I will describe behavioral and modeling evidence for a distributed connectionist account of morphological phenomena. In this account, morphology reflects a learned sensitivity to the systematic relationships among the surface forms of words and their meanings. This lexical knowledge emerges from the dynamic interactions of distributed patterns of neural activity representing phonology, semantics, and orthography.