This study demonstrated an e-learning system, MyEVA, based on a mixed-modality vocabulary strategy in assisting learners of English as a second language (L2 learners) to improve their vocabulary. To explore the learning effectiveness of MyEVA, the study compared four vocabulary-learning techniques, MyEVA in preference mode, MyEVA in basic mode, an Internet dictionary, and a traditional paper-based dictionary. The findings indicate that the mixed-modality with preference-mode setting stimulated the greatest vocabulary acquisition and the best retention for L2 students. The more proficient students in the study selected a preferred strategy that they employed consistently. Less proficient students did not select a preferred strategy and improved less than their more proficient fellow students. Researchers also provided recommendations for language teachers, curriculum designers, and in particular, the developers of English e-learning systems.