Vague language (e.g. thing, somewhere) is one of the linguistic features which typically differentiate the language use of a native or near-native speaker from that of a language learner since native speakers typically make abundant use of vague expressions. Thus far, however, there has been no published research on how features of pedagogic tasks might encourage L2 learnersÕ production of vague expressions. The present study sets out to examine whether and how task structure affects the number and type of vague expressions used by a group of higher-intermediate EFL learners. The participants were 50 Iranian EFL learners from six intact classes, all native speakers of Persian with limited opportunity to communicate with native speakers of English, and no experience in English-speaking countries. To elicit data, two picture description tasks were used. These picture-stories possessed the defining characteristics of structured and unstructured narrative tasks, respectively. Results revealed that (a) unstructured tasks were associated with the production of significantly more vague expressions; and (b) the most notable differences between performances on the two task types concerned Ôvague nounsÕ, Ôvague quantifiersÕ, Ôvague deintensifiersÕ and Ôvague subjectivisersÕ. The results of the study have implications for both teachers and teacher educators in that they may help identify the kinds of tasks which induce language learners to use vague expressions more frequently.