Language assessment is a broad concern in Applied Linguistics because it focuses on the measurement and judgment of learners’ proficiency, and the efficiency of the learning practice used by the learners as well as the teaching method employed by language teachers. This research paper adopted Evidence Centered Design (ECD) as its theoretical framework to form the bedrock of this study. The ECD methodology is an assessment approach or design which underscores the central sole of evidentiary reasoning in assessment. ECD assessment deisgn is used in this study to explore the efficiency of Evidence Centered Design in the assessment of English language proficiency level of the Igbo speakers of 200 undergraduates from three polytechnics and one college of education in Anambra State, Nigeria. The study adopted qualitative and quantitative research design, primary and secondary source of data to help the researcher make predictions and judge the communicative competence of these learners by using diagnostic model of test to determine their interactive knowledge in the use of parts of speech. The study used simple percentage which is the statistical analysis acceptable in Language studies, to analyze the data collected from the questionnaire and the test. The findings from this study proved the validity of ECD assessment in determining language proficiency.