This study investigated the effectiveness of using the flipped classroom strategy based- program in Islamic reading texts. The sample of the study consisted of (20) students at Al- Azhar Hurghada Ideal Institute for boys, Red Sea Governorate. It utilized the one group quasi-experimental design with its pre-post testing procedures. The instruments included a language skills checklist, a vocabulary acquisition test and a rubric for assessing the test. The study was conducted during the academic year 2020/2021. The results showed that there was a statistically significant difference between the mean scores of the participants in the pre and post-test of the Islamic English vocabulary acquisition test favoring the post-test. The study concluded that using the flipped classroom strategy based program proved to be effective and had considerable contributions in developing the Islamic vocabulary acquisition of the first-year secondary stage students at (0,988) which can be attributed to the experimental application of flipped classroom strategy.