Although substantial evidence exists showing written corrective feedback (WCF) helps second language (L2) learners improve their writing accuracy, there is a paucity of research that has examined L2 writing accuracy in connection with both revision behavior and processing of WCF. Using a quasi-experimental research design, 44 learners from four Academic and Professional Writing courses were divided into two groups: individual processing (n = 20) and collaborative processing (n = 24). The participants completed four timed writing tasks and received indirect WCF from a course teacher that used different error codes to target nine error types. The participants processed the WCF individually or collaboratively before revising. Participants’ revision behavior (the number of errors successfully resolved, unresolved, and abandoned) and writing accuracy (total number of errors and total number of errors by error type) were analyzed and compared. The results showed the collaborative processing group's performance in terms of resolved, unresolved, and abandoned errors was superior to the individual processing group. While both groups exhibited improvements in overall accuracy, the collaborative processing group produced fewer verb and word choice errors after collaboratively processing three rounds of WCF. The results are discussed in terms of the importance of L2 writing teachers’ pedagogical practices.