This study aims to determine the level of school administrator self-esteem and its relationship to school administrator trust in teachers. The research design is a relational survey. The study was conducted at K-12 schools (a total of 131 schools) in İzmit county in the Kocaeli province of Turkey. The data were gathered through a three-part questionnaire: the first part consisted of the Rosenberg (1989) self-esteem scale, a ten-item four-point Likert-type scale; the second part included a three-factor trustworthiness instrument with 17 items by Mayer and Davis (1999); and the third part was related to six demographic variables. SPSS 13.0 was used for data analysis. Descriptive and inferential statistical techniques were applied to the data. Findings revealed that administrators have very low levels of self-esteem. Their levels of trust in teachers were also found to be low in all three dimensions of trustworthiness that were affected by administrator self-esteem. Results indicated that administrator self-esteem, education level, and seniority as an administrator in the current school were positively correlated with trust; title, school level, and seniority as an administrator were negatively correlated.