Higher education institutions increasingly expect students to work effectively and critically with multiple modes, semiotic resources and digital tools. However, assessment practices are often insufficient to capture how multimodal artefacts represent disciplinary knowledge in complex ways. This study explores and theorises the design and assessment of students' digitally mediated multimodal work, and it offers insight into how to effectively communicate expectations and evaluate student learning in a digital age. We propose a framework for multimodal assessment that takes account of criticality, creativity, the holistic nature of these assignments and the importance of valuing multimodality.