The naming and drawing responses of a child with specific language impairment (age 5.5 years) were used to test the hypothesis that deficient storage in the mental lexicon plays a role in the naming problems associated with SLI. In confrontation- and repeated naming, the child demonstrated frequent semantic substitutions and occasional phonologic substitutions. Stochastic modelling of his repeated naming revealed storage deficits to be a source of these errors. Comparative picture naming, picture drawing allowed exploration of this storage deficit and revealed that, for some semantic naming errors, sparse semantic representations were clearly at fault but for others, sparse phonological input and output representations played a role. Phonological naming errors, in contrast, were typically associated with strong semantic representations. Clinical, theoretical, and methodological contributions of this cognitive neuropsychological case study are discussed.