Abstract This study investigated the effectiveness of learner autonomy strategies in promoting vocabulary acquisition among beginner English language learners (BELLs) in Saudi Arabia. An experimental design was employed to compare the vocabulary acquisition of BELLs who participated in a program promoting learner autonomy strategies with the acquisition of those who did not. The results indicated that while learner autonomy can be a valuable tool, it may require ongoing support and reinforcement to ensure long-term effectiveness. The study found that the experimental group, which received the autonomy intervention, consistently outperformed the control group, demonstrating significant improvements in vocabulary acquisition. However, the positive effects of autonomy were not sustained after the intervention ended. These findings suggest that while autonomy can lead to initial gains, it may not be sufficient on its own to maintain long-term improvements. Therefore, it is crucial to integrate continuous support mechanisms to maximize the benefits of learner autonomy strategies in vocabulary learning.