The arrival of the internet age forces academic journals to adjust their output margins: journal length, article length, and number of published articles. Using data from 41 major economics journals spanning 21 years (1994-2014), we find that both journals and articles are getting longer, but the page share of an individual article within its journal is shrinking. This pattern is consistent with a monopolistic competition model that features within-firm (journal) specialization. As predicted by the model, the share of an individual article shrinks less in general-interest journals and better ranked journals, where expertise is less substitutable across topics. In this discipline that emphasizes the benefits of specialization, the expertise underpinning its publications is indeed divided in a specialized fashion.