We propose an analysis of coordinate nouns in English that derives their derivational properties and interface differences. The proposed analysis adopts the hypothesis that the conjunction has an extended functional projection, just as other functional categories have, and that the derivation of these structures gives rise, in certain cases, to interface asymmetries. In addition to proposing a hierarchy of functional projections, this study also has consequences for child language development, challenging associative theories of learning and the idea that what appear to be simple nominal forms are reflexes of an earlier stage of the language.