The aim of this paper is to study the impact of introducing an integrative pedagogical approach in the ESP classes on developing the English language vocabulary of Computer Science and Information Technology students in the College of Science, Qassim University. The study suggests a framework for an ESP course-design employing students' project work based on the analysis of learners' needs. The researchers made use of the experimental pre-test post-test control group design where the English vocabulary test was used as a pre and post test. The results reported from this study revealed the effectiveness of the suggested project-based ESP course on developing the English vocabulary for the target subjects. Also, the results show that project based instruction enhanced the teaching and learning of ESP and developed new study habits for learners by promoting self-directed, independent, cooperative learning as well as out-of-classroom learning. The study concluded with recommendations related to how projects can be incorporated into ESP classrooms to develop different language skills i.e. speaking, listening, reading, and writing.