While recent literacy research shows an increasing uptake in multimodal literacies, there remains a disjunction between multimodal literacy teaching and assessment. This paper offers a critical review of assessment in the context of teaching multimodal literacies and begins by reviewing the notion of literacy and reframing assessment in educational contexts. In our review, assessing multimodal literacies is often located in studies of multimedia compositions as extensions of writing. Assessing multimodal literacies tends to take the form of rubrics and teachers' lack of knowledge in this domain of professional practice leads them to assessment criteria for writing as their point of reference. Research in higher education shows an emerging interest in engaging students in establishing criteria for assessing multimodal literacies. Elsewhere in English as an additional language/dialect and second language education, an embrace of multimodal tasks offers non-linguistic modes that can influence, engage and in some cases enhance students' multimodal communicative competence. Yet, researchers suggest multimodal literacies tasks are generally less valued for assessing literacies in these contexts. This article highlights the opportunities and challenges of assessing multimodal literacies and extends the ongoing debates for further research in closing the gap between teaching and assessing multimodal literacies.