This study aims to examine the relationship between school effectiveness and positive psychological capital in the context of public and private schools. The population of the research, in which the relational scanning method was used, consisted of 1296 teachers working in public secondary schools and private secondary schools in Tepebaşı in the 2018-2019 academic year; The sample is composed of 734 teachers reached by stratified ratio sampling method. "Psychological Capital Scale" and "Effective School Scale" were used to collect data. Descriptive and inferential statistics such as mean, standard deviation, correlation coefficients, and data analysis were used to analyse the data. According to teachers' opinions working in both public and private schools, when the findings obtained from the research were examined, there was a significant positive relationship between school effectiveness and the sub-dimensions of positive psychological capital. It was concluded that the teachers' effective school and positive psychological capital levels working in private schools were higher than the teachers working in public schools. A limited number of studies have been found in the literature examining the relationship between positive psychological capital and school effectiveness in the context of public and private schools. In this context, it is recommended to investigate the subject on different samples and at different levels.