The present study investigated the effect of different types of text simplification (i.e., reducing the lexical and syntactic complexity of texts) on reading comprehension of English as a Foreign Language learners (EFL). Sixty female intermediate EFL learners from three intact classes in Tabarestan Language Institute in Tehran participated in the study. The intact classes were assigned to three experimental groups. Moreover, to homogenize the groups, the researchers administered a general proficiency test (TOEFL, 2003) to the participants. The results revealed no significant difference among the groups in general proficiency and reading ability. Then four reading comprehension texts from TOEFL test (2005) were simplified through lexical simplification, syntactic simplification or lexical-syntactic simplification techniques. The simplified texts, along with their reading comprehension (RC) questions, formed the three versions of the post-test, each version contained either lexically, syntactically or lexical-syntactically simplified texts. Each group took one version of the post-test. The scores were analyzed through one-way ANOVA. The results revealed a significant difference among the groups. The post hoc test indicated that the lexical-syntactic simplification group significantly outperformed the lexical simplification group and performed considerably better than the syntactic simplification group. There was no significant difference between the lexical and syntactic simplification groups, although the latter showed better results.
