Human interaction is multimodal. ESOL K-12 teachers use multimodal learning resources (e.g., gestures, visual displays, digital teaching materials) to assist multilingual learners in understanding disciplinary knowledge, including mathematics. The purpose of this dissertation is to examine the perception and practices of ESOL teachers about the use of multimodal meaning-making resources in teaching mathematics to multilingual students. Additionally, from the social semiotic perspective, this dissertation uses the methodological framework of systemic functional multimodal discourse analysis in analyzing the meaning-making process of gestures and other digital teaching materials. The data for this dissertation includes semi-structured interviews with five ESOL teachers, classroom observations, field notes, and video recordings of a focal ESOL Algebra I class at a high school in the Southeastern United States These findings indicate the need for promoting awareness of the importance of using multimodal meaning resources in professional development, including the meaning-making processes of multimodal resources, and developing a methodological framework for choosing multimodal (including digital) teaching materials.