Development is implicit at every stage of appraisal irrespective of the approach; be it developmental (formative) or accountable (summative) (Bollington, Hopkins & West, 1993). If properly constructed and presented; the performance appraisal system can improve professional development of teachers, the management of the school, and students' learning outcomes. The focus of this study was to unpack the influences of performance appraisal on teachers' professional development. This study was conducted in one of the private schools in Karachi, Pakistan; and it involved ten participants, six appraisees, three appraisers and one reviewer. Data were collected using exploratory nature case study within the qualitative paradigm of research. Interviews and the document analysis were the major source of data collection. As a result of qualitative data analysis, the study has generated some findings related to the influence of performance appraisal on teachers' professional development. The study revealed that appraisees unanimously identified the purpose of appraisal as a summative assessment of teachers' performance for making administrative decisions such as; deciding annual increment and making teachers more accountable to school rule and regulations. The suggestions made by appraisees confirmed that the teachers did not perceive that there was a link between appraisal and the professional development of teachers. In contrast, the appraisers collectively considered performance appraisal as a tool to appreciate teachers' potentials and to identify areas for further enhancement. In addition, the findings of the study further suggest that the process of performance appraisal influences relations within teachers, and between teachers and supervisors negatively if handled in a less professional way. The findings of this study also suggest that a system of shared, informed and mutually agreed policy on performance appraisal should be developed by involving all key contributors and disseminated to all teachers to make the process clearer to all. This is also important to strengthen trust between teachers and the management of the school. The findings of this study may provide a useful insight to schools i.e. those who are in the process to introduce performance appraisal, or are reviewing their appraisal system and policies.