This study aimed at exploring the factors affecting classroom teachers' job performance. Maximum variation sampling was used to select the study group. 72 teachers working at primary schools in a province in Eastern Turkey participated in a qualitative dominant mixed-methods study incorporating a qualitative case study and Q methodology. The data obtained through interviews were content-analyzed, and the Q data were analyzed via the PQMethod 2.35 software program. The results indicated that organizational, managerial, and systemic factors had both negative and positive effects on teacher performance. Teachers expressed similar views via the item configurations provided and built up a similar profile about the factors affecting job performance. Besides general professional competencies, students' readiness level and teachers' mastery of course content were reported to have impacts on classroom teachers' job performance.