Integrated writing tasks that involve different language modalities such as reading and listening have increasingly been used as means to assess academic writing. Thus, there is a need for understanding how test-takers coordinate different skills to complete these tasks. This study explored second language writers’ strategy use and its relationship to test performance on an integrated reading-listening-writing test task using a structural equation modeling approach. The results reveal that integrated writing strategy use was a multifaceted construct consisting of three factors: self-regulatory strategy use (SELFS), discourse synthesis strategy use (DSS), and “test-wiseness” strategy use (TWS). SELFS had an executive control over other types of strategy use. DSS had a direct, positive impact on test performance, and TWS had a direct, negative impact on test performance. The study suggests that the task requires not only comprehension and production abilities, but also regulation skills for managing reading, listening, and writing interactions. The findings provide insight into the nature of integrated reading-listening-writing tasks and contribute to validity arguments for the test. The study has implications for second language academic writing assessment, learning, and instruction.