The purpose of this study was to identify the effect of using Modul Pembentukan Amalan in developing personality and leadership of preservice teacher. A quantitative approach using quasi-experimental method was applied in this study. A lecture method of teaching was implemented to the control group while Modul Pembentukan Amalan Profesionalisme was implemented to the treatment group. Data on the proficiency level were collected using pre-test and post-test by using case study test instruments which are equivalent to the study. A total of 70 preservice teachers were chosen as the subject of the study using intact sampling which involved 35 students from the Bachelor of Education in Entrepreneurship and Commerce, and 35 students from the Bachelor of Education in Business Management. Both programmes under the same department which is the Department of Business Management and Entrepreneurship, Faculty of Management and Economics, Sultan Idris Education University. Students the Entrepreneurship and Commerce Programme were chosen as control group and the students of Business Management Programme were set as the treatment group. The difference in mean level of preservice teachers’ professionalism practice was analyzed using the t-test. The findings showed that the teaching and learning using the Modul Pembentukan Amalan Profesionalisme as an intervention in the treatment group could improve the professionalism practice of preservice teachers in terms of personality and leadership. However, a more comprehensive study issuggested to be carried out to ensure that the results obtained from thisstudy are robust and consistent.