This study investigated how 22 advanced-low proficiency ESL students used computer-based multimodal composing activities (CBMCAs) to facilitate self-revision and learn English through academic writing in the USA. The CBMCAs involved a combination of writing, listening, visual analysis, and speaking activities. The research was framed within an integrated theoretical framework of multimodality, the noticing hypothesis, and the multi-dimensional model of revision. Data include surveys, students' revision history, online multimodal posters, reflections, screen recordings of listening activities, stimulated recall interviews, final written drafts, and scores on those drafts. Data collection and analysis followed a descriptive case study design with embedded quantitative data. Findings indicate that CBMCAs helped students discover specific rhetorical and linguistic elements that they used to revise their written drafts. In addition, students reported that the activities helped them develop language and voice to convey ideas that they were struggling to express using the written mode alone. Contrary to findings in most previous research, the students did more content-level than surface-level revisions. Also, there was a significant correlation between total frequency of revision and text quality. The practical and theoretical implications of these findings for L2 writing pedagogy and research are discussed.