This peer commentary emphasizes the importance of placing frequency in an overarching theoretical framework of language acquisition. Three issues are raised that appear to be both important and timely: (a) the question of how innate, or initial, cognition can deal with stimulus frequency; (b) the likelihood that frequency has a differential impact depending on the type of knowledge concerned; and (c) preliminary evidence that frequency affects receptive language knowledge more than productive knowledge, which raises the issue of a possible dissociation between the two knowledge types.