Familiarity with different aspects of English humor, which is used by native speakers in their daily communication, could enable learners to understand humorous expressions that might be otherwise literally vague or pointless to them. Therefore, the current study attempted to find out whether Iranian EFL learners recognize, comprehend, and appreciate English humor. To this aim, 82 female learners at intermediate and upper-intermediate level of proficiency were selected and English humor was taught to them. Three questionnaires were designed to examine the effect of lexical and grammatical knowledge on recognition, comprehension, and appreciation of English humor as well as the effect of instruction on the three variables. The results of two MANOVAs revealed that knowledge of vocabulary and grammar did not have any significant impact on recognition, comprehension, and appreciation of humor; whereas, familiarizing learners with structural and socio-cultural aspects like common formats, topics, and targets of English humor affected the EFL learners' recognition, comprehension and appreciation of English humor significantly
