As a large-scale standardized English proficiency test, IELTS attracts millions of test takers internationally. This essay, drawing on current theories in language testing and assessment, attempts to evaluate the writing test of the IELTS Academic Mod?ule. It is concluded that it is a generally valid and reliable test which generates overall beneficial effects, though several threats pos?sibly undermine its test validity and reliability. Some suggestions on improvement are proposed at the end.