This paper presents the theoretical and empirical foundations of the "TOEFL Junior"® assessment and its development process. The TOEFL Junior test was developed to address the increasing need for objective measures of English language proficiency for young adolescent learners, who are being introduced to English as a second or foreign language at a much younger age than ever before. This paper presents the test purposes and intended uses, target population, target language use domains, and test constructs of the TOEFL Junior test. Also included is a description of the overall test structure and scoring system, which demonstrates how the constructs are operationalized. Finally, we outline research topics to support the interpretive argument of the use of the test.This document is expected to serve as a reference point during investigations of validity evidence to support the intended test uses over time.