Blended learning is a pragmatic approach to education, combining online and traditional methods, applied extensively in the fields of English as a first, second and foreign language. The present study examined the effectiveness of the blended learning approach for the development of the reading skills of undergraduate students. Participants were 60 Thai students divided into experimental and control groups. Post-tests of each group were used as the main method of data collection, with a t-test being utilized to examine any differences between post-test scores. Statistically significant differences (t = 32.098; sig = 0.000) were investigated for effect size utilizing a Cohen'd test. Results revealed a significant effect size (Cohen'd = 3.937). The implications of this study suggest that the implementation of blended learning could considerably improve the English language reading skills of undergraduate students studying English as a foreign language.