The present study investigated the effects of in-text parenthetical glossing on incidental vocabulary acquisition of English learners reading experiments.English-major sophomores from three parallel classes participated in the study.In the experiment,the control class was given the reading material with no glossing while the experimental classes were given the L1-glossing version and the L2-glossing version respectively.The results showed that there was no significant difference between the control class and the experimental classes in the immediate word-form identification test and the form-meaning matching test.In other words,in-text parenthetical glossing,different from other forms of glossing,is not proved to be significantly helpful for L2 learners'incidental vocabulary acquisition through reading.