SUMMARY: This study investigated whether proficiency in a particular language skill (e.g., speaking) could be better estimated by considering not only the TOEIC test scores corresponding to that skill, but also TOEIC tests scores for other skills. The results supported this assertion, suggesting that scores on the four-skill TOEIC tests together provide a more valid measurement of English-language proficiency than any skill in isolation. (The findings of this externally published report are consistent with the ETS-published report The TOEIC Listening, Reading, Speaking and Writing Tests: Evaluating Their Unique Contribution to Assessing English-Language Proficiency.)