This study investigated the effects of dialogic tasks on Iranian English as Foreign Language learners' language learning anxiety considering the moderating effects of the learners’ gender and levels of proficiency as well. A total number of 213 male and female Iranian EFL learners within the age range of 15-19 were selected through convenience sampling from three language schools in Fars, Iran. Learners at two levels of proficiency (upper vs. lower intermediate), were chosen and assigned to experimental and control groups. Then, an adapted translated version of Foreign Language Classroom Anxiety Scale (Horwitz et al., 1986) was run as a pretest and posttest to measure the learners’ anxiety. The treatment was dialogic tasks operationalized through sequencing picture stories. The results revealed that dialogic tasks exerted a significant effect on reducing Iranian EFL learners' anxiety. Moreover, it was discovered that upper-intermediate learners experienced lower levels of anxiety than their lower-intermediate counterparts. Finally, it was found that female learners in this study suffered from more anxiety levels than male learners. Although integrating dialogic tasks into classroom activities has proved to be beneficial as learners could experience sufficient opportunities for speaking, this task could not assist learners of different levels of proficiency and gender in the same way. These findings will provide practical implications for language teachers and learners.