AbstractThis study investigated how repeating a video‐lecture‐based task affects second language (L2) learners’ processing and incidental acquisition of technical vocabulary as well as the relationship between processing and lexical gains. The participants were 75 Chinese learners of L2 English. Thirty participants performed the task once (control group), whereas another 30 participants did the same task three times (repetition group). The two groups then completed unannounced vocabulary posttests. The remaining participants engaged in stimulated recall after performing the task once, twice, or three times. The repetition group made greater gains in vocabulary knowledge than the control group, and the repetition group's visual attention to the target words declined during repeated viewing. The amount of attention to the target words emerged as a predictor of delayed meaning recall, with task repetition decreasing the strength of this relationship. Stimulated‐recall participants repeating the task reported increased awareness of specific aspects of the target words.