This systematic literature review was undertaken primarily to examine the role that print and digitally mediums play in text comprehension. Overall, results suggest that medium plays an influential role under certain text or task conditions or for certain readers. Additional goals were to identify how researchers defined and measured comprehension, and the various trends that have emerged over the past 25 years, since Dillon's review. Analysis showed that relatively few researchers defined either reading or digital reading, and that the majority of studies relied on researcher-developed measures. Three types of trends were identified in this body of work: incremental (significant increase; e.g., number of studies conducted, variety of digital devices used), stationary (relative stability; e.g., research setting, chose of participants), and iterative (wide fluctuation; e.g., text length, text manipulations). The review concludes by considering the significance of these findings for future empirical research on reading in print or digital mediums.