This study aimed at evaluating the effectiveness of the role-play as the teaching and formative assessment strategy for the undergraduate English major students from the Riyadh region of Saudi Arabia. To find the effectiveness and the impact of role-play as a teaching strategy, a quasi-experimental method was employed by using a pretest-posttest design wherein the pre and posttest results of 70 EFL students from experimental and the control groups were compared. The experimental group was taught some new areas of grammar, functions and vocabulary using role-play; simultaneously, the control group was taught the same items using the traditional method of teaching. The pretest revealed no significant difference in the knowledge level of the students between the two groups. On the other hand, the posttest results showed that there was a significant difference in the knowledge level of the students in favour of the experimental group. Further, a structured questionnaire was used to understand the perspective of the teachers on the efficacy of role-play in the assessment of students in the English language classes. A sample size of 20 teachers was used where it was found that role-play had a significant impact on the formative assessment. The findings of the study suggested role-play as an effective technique for the undergraduate English-major students in Saudi Arabia to solve the classroom interpersonal troubles, and it would help the students to imbibe the human-relation along with increasing their proficiency in the English language.