Reading is as essential as other communicative skills; however, reading practice is not likely to be the first choice of practice for learners. This is especially true among Thai learners. This study examines extensive reading (ER), otherwise known as reading for pleasure or wide reading in combination with interactive groups to investigate the effects on Thai undergraduate students' reading ability, and their opinions toward their reading development, including an exploration of self-autonomous development. The study was a mix-method study with 30 students from a university in Thailand who voluntary participated for a 10-week study. Results from the pre-test scores (M = 13.17, SD = 4.58) and post-test scores (M= 20.73, SD = 6.28) indicate that there was a significant increase in the reading scores, t(29) = - 6.3, p = 0.000. The results suggest that extensive reading activities are likely to contribute to participants' reading skill improvement. In addition to the quantitative analysis, the qualitative interview analysis also revealed that participants maintained a positive attitude towards their reading skill development and self-autonomous skills.