The present study compares the effects of the second language (L2) reading and listening on incidental vocabulary learning and retention of three dimensions of word knowledge (i.e., part of speech, syntagmatic association, and form-meaning connection) among EFL learners. The relationship between word exposure frequency and vocabulary learning is also examined in reading versus listening. Sixty-three pre-intermediate EFL learners in four intact classes were randomly assigned to four experimental groups based on the number of target word (TW) exposures (i.e., 1, 3, 5, and 7 exposures) they received in treatment texts. The experimental groups read and listened to four texts with 36 TWs. The scores on the immediate and three-week delayed posttests revealed that reading contributed to a greater amount of vocabulary learning and retention in the three dimensions of word knowledge. The results further revealed that an increase in the word exposure frequency had a significant effect on acquiring form-meaning connection through reading, and on three dimensions through listening. Moreover, frequency improved retention gains in both input sources.
