abstract since heubners (1985) pioneering study, there have been many studies on (mis) use/ non-use of articles by l2 learners from article-less and article languages. the present study investigated how persian l2 learners of english produce and interpret english definite descriptions and demonstrative descriptions. it was assumed that definite and demonstrative descriptions share the same central semantics of uniqueness, although they differ in the domain relative to which uniqueness is computed. while the book denotes the unique book in the discourse, that book denotes the unique book in the immediately salient situation. persian has demonstratives and is partially marked for specificity, while english encodes definiteness. persian l2 learners, due to lack of an equivalent for english definite marker the in their language, use demonstratives as one of the compensating mechanisms to encode definiteness in definite descriptive contexts. a forced-choice elicitation production task and a picture-based comprehension task were used to examine the l2 learners ability to distinguish definite and demonstrative contexts. l2 learners were able to acquire both definite and demonstrative descriptions, but were more target-like regarding demonstratives than definite descriptions. the variability in choosing articles and demonstrative adjectives in one specific context (e.g. applying both the and that in contexts specific to the only or that only) shows that persian efl learners equate ?n with both the and that. this, also indicates that l1 transfer determines the l2 learners choices. the theoretical and pedagogical implications of the study will also be discussed. keywords: articles, definiteness, demonstratives, descriptions, determiners, semantics, l1 transfer