This article reports on the causal relationships between three factors in second language (L2) group work settings: communication confidence (i.e., confidence in one's ability to communicate), beliefs about group work, and willingness to communicate (WTC). A questionnaire was administered to 729 first-year university students in Japan. A model that reflected the hypothesis that WTC in L2 group work would be influenced by Beliefs in L2 Group Work strengthened by Communication Confidence was constructed and tested. Data were randomly split in two, with one-half used for model specification and the other half for confirmation. The structural equation modeling confirmed this hypothesis, which implies that L2 WTC and WTC in L2 group work differed. This model marks the first step toward identifying the causal relationships among factors that affect WTC in L2 group work. (Contains 4 figures and 3 tables.)