While research on digital multimodal composing (DMC) has been skewed towards the instructional design and affordances of DMC for L2 learners, there is a wider need to develop conceptual models of L2 DMC competence, with which L2 learners can successfully design DMC works and respond to the multimodal reading and writing demands of the digital era. To date, the studies on DMC competence have primarily taken an etic approach to identifying the salient features of effective DMC samples or examining teachers’ perceptions of L2 student DMC competence. Few, however, have taken an emic approach to capturing the DMC competence from the perspective of L2 learners who have first-hand participatory experiences in designing DMC works. Therefore, the present study addresses the research gap by taking an emic approach to examining L2 student DMC competence through student focus group interviews with ten groups of students, classroom observations of student self and peer feedback on digital multimodal compositions, and DMC sample analysis. The clarification of L2 DMC competence can guide the measurement and instruction of L2 DMC competence, promote the integration of DMC competence into the L2 curriculum, and drive L2 learners to engage with self-assessment of DMC competence to develop their DMC competence.