This study investigates the effect of preschool teachers' collective self-efficacy. A study group consists of 172 preschool teachers who are working in public preschools affiliated with the Ministry of National Education in different cities of Turkey. In this study, teacher self-efficiency scale is employed to assess professional efficiency perception of teachers. Schwarzer et al have developed the scale, Sünbül and Arslan studied validity and validity of scale, and adopted it to Turkish. For identifying teachers' collective self-efficacy, the Collective Teachers' Self-Efficacy Scale developed by Arslan and Sünbül (2006) has been applied. In data analysis, Pearson product-moment correlation, and simple linear regression analysis method has been used. As a result of the study, it was found that there was a positive relationship between teachers' self-efficacy and collective self-efficacy. Besides, it was found that teachers' self-efficacy significantly explain collective self-efficacy.