Vocabulary building as the foot-stone of the whole language learning, lays the foundation for students learning English vocabulary and using various English learning strategies rationally (Gruneberg, 2007). While the team-teaching method is one of the efficient teaching methods to learn new concepts .Therefore, this study was design to investigate the effect of team teaching on English vocabulary building of grade 7 students. The study followed the positivist philosophical research paradigm followed by true experimental pre-test post-test control group design. A sample of 60 students studying in an X school was selected (i.e. 30 students= experimental, 30 students= control group). Pre-test and post-test were taken to determine the effect of team teaching on English vocabulary building of student before and after the intervention. Control group was taught English through traditional method whereas experimental group was taught the lessons by team teaching method. Validity of the instrument was censured by experts. Reliability of the instrument calculated using split half method was 0.71. Results of the pre-test showed that there is no statically significant difference found in the scores of the experimental group and control group (p>.05). After 10 weeks of intervention period, post-test was taken which exposed that there is statistically momentous difference in the academic achievement of the students have been taught by team teaching method (p
Key words: Team teaching, vocabulary building, English language, intervention.