This qualitative case study aimed to explore teachers' experiences and practices of developing teaching portfolio (TP) in a private, primary school where teachers were engaged in this practice for five years after implementation of a new teacher evaluation system called Performance and Management Reward System (PMRS). TP was introduced in the school because it has gained a significant value internationally as one of the authentic sources of teacher evaluation and continuous learning. TP is considered as a vehicle that promotes reflective practices and provides avenues of self-analysis through which one can assess own strengths and weaknesses and plan a way forward. It was significant to investigate teachers' perspectives in this regard to facilitate them in accordance with literature. Using purposive sampling approach, four female participants and the vice principal were interviewed. Furthermore, teachers' portfolios were reviewed and the PMRS guidebook was studied for the triangulation of data collected through interviews. The study reveals that teachers' have dualistic perspectives about portfolio. They feel that developing teaching portfolio is assisting them in their professional growth in multiple ways such as through self-reflection on their lessons, by documenting their professional development (PD) log and thinking of their professional goals for future. Simultaneously, they also consider it as a mandatory task to be done for the appraisal evaluation. Moreover, during the process various challenges were encountered by teachers. These include difficulty in writing reflection, time constrain, thinking of future goals, and getting coloured printouts for the portfolio file. Hence, the need for continuous assistance to teachers merged. Moreover, development of portfolio appeared as a product and one time activity that take place towards the end of the academic year for the appraisal evaluation. Therefore, it is recommended that a structured mechanism of mentoring should be established in the school to facilitate teachers throughout the process of developing portfolios. This will also facilitate teachers to improve their reflective practices. This study contributes to the body of knowledge about TP particularly in Pakistani context.