Technology has triggered the appearance of digital textbook in education especially in English. Digital textbook is an electronic version of printed books which has been popular in education. Several related studies had confirmed the advantages of using digital textbook for ESL learners. This study was conducted to explore the effectiveness of digital textbook in increasing learners' proficiency in English. The study with fifty seven participants was a true experimental research which applied

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... etest-posttest control group design. Having two groups of participants (experimental and control), this research was conducted by selecting the participants randomly, administering pretest, giving treatment, administering posttest, analyzing the data and interpreting the results. This research found that even though data was not normally distributed, the data still had the same variances. Therefore, the independent t-test in this research used Wilcoxon Signed Rank Test. The results discovered that the t value was 0.30 which was lower than 0.050. It indicated that the treatment was significantly effective in this research. In other words, this research revealed that digital textbook had contributed positively to the learners' English achievement as it was seen from the better performance of the experimental group than the control group.