Teacher Performance Appraisal (TPA) or evaluation has been in practice in many private schools in Pakistan since the past years. The main purpose behind TPA is performance improvement through professional development and accountability of the teaching staff in the schools. Normally, it is assumed that too much emphasis on professional development could easily overlook the importance of the teachers' personal lives. Thus, this study is to explore how appraisers and appraisees experience TPA in the school under such circumstances. In order to understand the experiences of appraisers and appraisees, I conducted a qualitative case study in a private school in Karachi, Pakistan. The school has been exercising TPA for many years for the purpose of professional development and accountability of its staff. The data were generated from five research participants and non participants through interviews, document analysis and observations. Unlike many studies on TPA, this study reveals that the appraisees' personal lives are influenced by their professional lives or vice versa, because too many activities in the name of professional development and performance improvement affect the personal lives of appraisees. The appraisees have to carry out many responsibilities that compel them to stay in the school after school hours; they come to school even on holidays and carry the work home. Such extra duties negatively influence the lives of the appraisees and particularly the female employees working in the school. However, the findings also show strengths and weaknesses in the existing TPA scheme in the school. Thus, the study suggests that for effective appraisal process, it is important to take into account the individual differences and personal backgrounds of appraisees, during the process of appraisal in the school. Furthermore, training and workshop for appraisers and appraisees, self-evaluation system and mentoring could be helpful steps that a school can take to make the appraisal system more effective and systematic.