with the introduction of communicative language teaching, a large number of studies have concerned with students’ oral participation in language classrooms. although the importance of classroom participation is evident, some language learners are unwilling to engage in oral activities. this passivity and unwillingness to participate in language classroom discussions is known as “reticence”. reviewing the literature on language learners’ reticence revealed that reticence is one of the main hindering factors in learners’ language learning. hence, the present study aimed to examine the reticence concerning iranian efl learners at tertiary level, and to discover any possible relationship between the learners’ reticence and their vocabulary knowledge, and their foreign language classroom anxiety (flca). moreover, it tried to determine the difference between male and female learners’ level of reticence. to this end, 56 iranian efl students from university of sistan and baluchestan and islamic azad university of zahedan participated in this study. the unwillingness-to-communicate scale as well as the foreign language classroom anxiety scale was run to obtain the learners’ level of reticence and anxiety respectively. moreover, the vocabulary-size test of controlled productive ability was administered to measure the learners’ vocabulary knowledge. the analyses of the data showed relatively a low level of reticence in the learners. in addition, the following results were found: the learners’ reticence in speaking has significant relationship with their vocabulary knowledge. in other words, the higher the level of the learners’ vocabulary knowledge is, the more reluctant they are to oral participation. furthermore, the learners’ reticence is significantly related to their feeling of anxiety in fl classroom. that is, the more anxious the learners are, the more their unwillingness to communicate with others. finally, the result of t-test showed that there was no significant difference between the male and female learners regarding their reticence level. these findings indicated that the various variables, such as vocabulary knowledge and anxiety can lead to learners’ reticence in class activities. as it is a challenging matter for both the efl teachers and learners and affects the students’ success in fl classes, it is crucial and necessary that the teachers assist their reticent learners to develop the required language skills and enough confidence for an active participation in oral activities.