To shed light on the dynamic interplay between collaborative writing research and its application in L2 contexts, this paper discusses three critical relationships. The first relationship focuses on research findings that have been reasonably well applied in practice, highlighting areas such as activity types and grouping strategies in collaborative writing, computer-mediated collaborative writing, and the impact of collaborative writing activities on student writing performance. The second relationship examines areas where research findings have not been sufficiently applied in practice, including the quality of student interactions, the emotional experiences of students during collaborative writing, and the long-term effects of collaborative writing on individual writing development. The last relationship identifies issues that are under-represented in research but are crucial in practice, such as feedback and evaluation practices, individual learner development, and pre-writing training in collaborative writing. For the second and third relationships, marked by mismatches between research and practice, implications are drawn to help teachers apply research insights and encourage researchers to address practical priorities. In conclusion, the paper provides suggestions to address each of the relationships to strengthen the research-practice link.