The aim of the study is to investigate effectiveness of teaching the Book English Unlimited Special Edition 1 (EUSE) on Developing Speaking Skill for Students of Preparatory Year of Al-Baha University. In order to answer the questions of the study, the researcher adopted the experimental approach. The sample of the study consisted of (50) students of preparatory year of AlBaha University. The speaking skills integrated in the set book were used with the study group in the first term of the academic school year (2019 – 2020). A test of (20) items was designed to be used as a pre -posttest. The study indicated that there are statistically significant differences in mean scores of speaking skills test in favor of the post application. Speaking skills (request, suggestion and asking for directions) included in the taught course (EUSE 1) book are convenient to enhance those students’ understanding and language progress. They can be considered as a remedial program to what they lacked in secondary schools as well as upgrading preparatory year students’ levels. In the light of these results, the study recommended the suitability of using Unlimited Special Edition (EUSE) for developing Speaking Skill for Students of preparatory year of Al-Baha University. It also suggested that further research should be conducted on the role of teaching listening to enhance speaking skill for students of preparatory students at Al-Baha University .