abstract the present study was conducted to examine the effect of proficiency on students interaction while carrying out the grammar-based task(s) in collaboration. in particular, the study examines whether the level of proficiency affects the learners’ focus of attention to grammatical and lexical features. the study takes a further step and examines whether there is any difference in the use of meta-language terminology in the grammatical episodes between the high-high and low-low dyads of learners. finally the present study explores whether learners’ metatalk (their correct resolution of lres in the tasks) influences their subsequent individual performance. twenty four efl learners attending two different classes in a private language school in iran participated in the study. the students in each class were assigned to pairs and performed four collaborative tasks: cloze passage, unscrambled sentence task, sentence-editing task, and spot the difference task. after recording pairs of learners one at a time, the researcher transcribed the data and analyzed them in terms of the number, type, and outcome of language-related episodes. the participants’ subsequent individual performance was assessed using a tailor-made dyad specific test administered two weeks after the experiment. the results of the study indicated that a) there was no significant difference in the number of lres between the high-high and low-low proficiency dyads of learners in grammar-based tasks; b) learners with high level of proficiency primarily focused on grammatical forms, but no significant difference was found between high and low dyads in their focus on lexical items; c) both high-high and low-low dyads used meta-language terminology and they did not differ in this regard d) the subsequent individual performance of both groups of learners was affected by the correct resolution of lres obtained during task performance; furthermore, the more proficient learners progressed more than the less proficient learners. key words: efl context, proficiency level, language-related episode, focus of attention, collaborative dialogue, transfer of knowledge