In this paper, I investigate the phenomenon of morphological variability in the production of Italian determiners, descriptive adjectives, and direct object pronouns by adult English learners of Italian to determine whether morphological errors are the result of computational or representational difficulties. Second language acquisitionists do seem to agree on whether erroneous morphological forms noticeable even in advanced second language grammars due to the absence of the functional apparatus responsible for their feature-checking, a partially developed morphological competence, or even learners' performance limitations. Data have shown that the morphological features of Italian Determiner Phrases (DPs) and pronouns are fully acquirable, despite their absence in the grammar of learners' native language. Furthermore, adult English speakers' precocious familiarity with Italian nominal and pronominal morphology, and the uniform occurrence of erroneous forms in their interlanguage grammars suggest that morphological variability does not stem from the absence of the necessary functional structure, but from a general deficiency in properly "assembling" the morphological features of a particular lexical item, and learners' inability to map them with the syntactic information available. (Contains 7 tables and 2 footnotes.)