This article examines the washback effect of standardized English language tests, such as TOEFL and IELTS, on teaching and learning processes. The study analyzes both positive and negative impacts of high-stakes testing on educational practices. Positive washback is identified in the promotion of comprehensive skill development, clear goal setting, and enhanced learner motivation. Conversely, negative washback manifests through "teaching to the test," reduced creativity, and increased student anxiety. The role of teachers and policymakers in mitigating adverse effects and fostering authentic language competence is discussed. The findings suggest that aligning test design with communicative language teaching principles is essential for maximizing positive washback and improving overall educational quality.