This research is based on the idea that teachers' performance at school level directly contributes to school effectiveness by achieving their educational objectives. In the research, relational scanning model, which is one of the screening models, was used. 426 teachers (286 women and 140 men) participated in the study. Data were collected through School Effectiveness Scale (Hoy, 2014) and Teacher Performance Evaluation Scale (Özgenel, 2019). Data were having been analyzed by t test, ANOVA, correlation and regression. According to the research findings, teachers' perceptions of school effectiveness do not show significant differences according to their gender and seniority; but according to their educational background and school level. School effectiveness perceptions of undergraduate teachers are higher than those of graduate teachers. Primary and secondary school teachers perceive their schools more effectively than high school teachers. While teachers' performances do not show significant differences according to their educational background and seniority; it shows according to their gender and school levels. The performance of female teachers is higher than male teachers. Primary and secondary school teachers' performances are higher than those of high school teachers. Teachers' performance decreases as the school level progresses from primary, secondary and high school. A moderate and positive relationship was found between teachers 'performances and school effectiveness (r=.358; p<.01) and teachers' performances was explained 12% of the total variance in school effectiveness. In other words, teachers' performances positively affect the effectiveness of school. In the study, it was concluded that teachers' performance predicted school effectiveness and positively influenced. When it is recognized that building effective schools is a difficult process, teachers are expected to be involving and perform at a high level in order to overcome these challenges and achieve the school's basic objectives at the desired level. Therefore, it may be recommended to policy makers and school leaders that teachers determine their performance, receive feedback and establish a performance evaluation system with improvements as a result of the performance evaluation process.

School Effectiveness, Performance, Teacher Performance