Abstract-This study aimed at examining the use of concept mapping technique in a course module for Korean language learning with U.S. college students, who were prompted to engage in collaborative writing planning. The study assumed that concept mapping enhances students' communicative interaction to promote their L2 writing. One hundred and twenty-three participants were recruited from three different proficiency level classes (beginning, intermediate, and advanced classes). Data were collected during three writing sessions: pretest of writing, individual planning, and collaborative planning. The MANCOVA results on the five components of composition score showed that the effect of collaborative concept mapping on L2 writing significantly differed across the three class levels. The study suggested practical implications for the use of collaborative mapping tasks in L2 writing contexts.Index Terms-Collaborative language learning, concept mapping, prewriting strategy, second language writing learning.