Applied linguistics and Computer-Assisted Language Learning (CALL) continue to witness a multimodal and semiotic turn because speech and writing as the main modes of communication are no longer fit for contemporary and increasingly digital communication. Multimodal texts, such as digital stories and social media posts, are more complex and require more nuanced meaning-making processes. Semiotic approaches in CALL draw on semiotics—the study of signs and symbols and their interpretation—to understand how learners engage with and make sense of technological tools in language learning contexts. Various symbolic systems and tools for meaning-making are considered within the communicative process. This requires a focus on all modes and semiotic resources available in the space within which learning takes place, such as gesture, images, sounds, objects, as well as speech and writing as part of either physical, mobile, virtual, or augmented spaces. This entry first introduces the key concepts (signs and symbols, multimodality, affordances and constraints, cultural context, design and user experience, and critical perspectives) and theoretical foundations of semiotics as implemented in pedagogical approaches of CALL, including systemic functional linguistics, geo-semiotics, and social semiotics. It then explores a number of practical and pedagogical applications, such as digital storytelling, multimodal composing, activities for visual literacy and multiliteracies, online collaborative tasks transcending geographical boundaries, and engagement with digital artefacts. It concludes with a discussion of challenges, such as those for assessment, ethics, and future directions.