This study investigates the relationship between language proficiency and academic achievement from sociolinguistic points of view. Literature and related research on interpreting language proficiency in relation to academic achievement are primarily examined and discussed. The study reviews the predicative validity for academic achievement of the Test of English as a Foreign Language (TOEFL) and other standardized tests that are commonly used in most American and Canadian colleges and universities for admission procedures. This research provides insight into counseling procedures toward improving the students' academic success. particularly for those who are currently studying or intend to go abroad for studying in English-speaking countries.