Pierce, Genesee, Delcenserie, and Morgan (2017) are right to propose that working memory is a pivotal part of the machinery underlying linguistic development. This brief commentary moves beyond the emergence of phonological representations, on which Pierce et al.’s essay centers, and considers ways in which working memory molds the character and acquisition of grammatical phenomena, a topic that has been examined in several ways in the recent literature (e.g., Chater & Christiansen, 2010; Hawkins, 2014; O'Grady, 2005, 2015).