Key accounts of morphological variability in L2 acquisition posit either deficits in the representation of abstract morphosyntactic features or the mapping between morpho-phonological forms and syntactic features due to computational limitations. This study extends previous research to L2 Italian, a richly inflected language. The production and grammatical intuitions of suppletive and affixal verb inflection were elicited from a cross-section of instructed adult L2 learners with L1 Spanish and L1 English. Although a clear production-intuition gap was found, supporting computational views, a strong regularity in the degree of variability across test conditions, L1s, and proficiency levels was also attested, supporting representational accounts. The findings suggest morphological development in L2 Italian is consistent with structure-building models that assume no L1 transfer of functional features. Imperative verb forms in L2 Italian are proposed as defaults equivalent to the bare verb forms of L2 English and non-finite defaults of L2 French and German.