This study investigated L2 learners' acquisition of three vocabulary knowledge dimensions through listening: form recognition, grammar recognition, and meaning recall. Whereas previous listening studies used only meaning-based vocabulary tests, which revealed very little vocabulary learning, the results of this study shows that learners start developing knowledge of a word (i.e. form and grammar recognition) long before they master the form-meaning link. Knowledge of the three dimensions immediately after listening was form > grammar > meaning, with the former two being more sensitive to attrition than the last. The effect of frequency of occurrence (3, 7, 11, or 15 exposures) on acquisition also differed between the three dimensions, but this effect was not strong overall. The acquisition of word meaning seemed particularly unaffected by frequency, a finding reminiscent of research on incidental learning from reading. For listening to be a valuable source for vocabulary learning, it appears that considerably more than 15 exposures are needed.