This study investigates whether grammar and pragmatics are separate linguistic components or not, and whether children with SLI and children with HFA have overlapping or distinct linguistic profiles. The study examines two DP-related phenomena: the mass-count distinction (grammatical) and the choice for a definite/indefinite article (pragmatic). It tested 27 children with HFA aged 6–14, age and gender matched to 27 children with SLI, and 27 TD controls on a Quantity Judgment Task (mass-count) and an Elicited Production Task (article choice). The results show that pragmatics can be impaired independently from grammar (in HFA) and vice versa (in SLI), providing evidence for a modular view of grammar and pragmatics, and against an overlap in the profiles of SLI and HFA.