The importance of incidental word learning through reading in order to expand second language learners’ vocabulary knowledge is not hidden to anyone. It is generally agreed that after learners learn their first thousand words through intentional learning, extensive reading is the task which can help them acquire more words. One important factor to be noticed is finding suitable reading materials which can better assist readers to learn new words which they face in the texts. The role and influence of two of the commonest text genres i.e. narrative and expository texts in incidental word learning have been a controversial issue among researchers. In this regard, the present study attempts to investigate the possible relationship between reading narrative and expository texts and immediate and delayed recall of incidentally acquired new words by Iranian EFL learners. To do so, two homogenous groups of Persian speaking EFL male and female learners studying English in Novin Institute in Arak participated in this study. The two experimental groups were named Narrative and Expository based on the texts they read. Three pairs of texts were selected; in each pair, there was one expository text and one narrative text with the same target words, length, theme, and difficulty level. Both groups participated in three immediate recall tests after reading their texts, and one delayed recall test which was administered after one month. The results of the tests showed that participants of Narrative group outperformed Expository group in terms of delayed recall of target words. On the other hand, Expository group performed significantly better than Narrative group regarding immediate recall. Concerning the total performance of both groups, it was found that Expository group performed better, but their difference was not statistically significant.
