While multimodality and multiliteracies has been a concept for 25 years (Kalantzis & Cope, 2023; The New London Group, 1996), research on and application of the concept within text complexity measures has been limited. Attempts to assess multiliteracies and multimodality (Jacobs, 2013; Schmerbeck & Lucht, 2017; Wyatt-Smith & Kimber, 2009) have primarily relied on qualitative or subjective assessments of multimodality. This dissertation seeks to study and compare the validity and reliability of two tools designed to assess multimodality quantitatively. Based around a theoretical clarification of the New London Group's original concept, these tools will allow researchers to assess multimodality in unique and helpful ways. Ultimately, the Quantitative Evaluation of Multimodality Tool was found to be both reliable and valid. Discussions for its implementation and understanding its results as well as the limitations of the study are discussed. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]