Could learning to read and write affect speakers' mental grammars? This book explores how literacy (or the lack thereof) shapes the comprehension and production of complex syntax among literate and illiterate speakers. Through innovative research, it reveals that native speakers do not always converge on the same grammatical structures, highlighting the pivotal role of written language in facilitating this acquisition. For those without literacy experience, nonverbal reasoning ability plays a crucial role in compensating for the lack of literacy when dealing with (complex) syntax. Literacy at Work challenges conventional views and offers fresh insights into the nature of linguistic competence.