The aim of this research is to reflect the description of teachers working in the secondary schools of TRNC on the managerial effectiveness skills of school administrators from the same schools and to identify whether their managerial effectiveness skills vary significantly on the basis of some variables. The research was conducted on a study group (sample) comprised of 369 teachers from 10 secondary schools. The study is a descriptive research conducted through screening with quantitative method. The Scale for Evaluation of the Effectiveness of School Administrators developed by Koçak and Helvacı (2011) was used as the data collection tool for this study with 3/5 dimensions. The research data were analysed through SPSS 23.0 software; and descriptive statistical processes were utilised as one-way analysis of variance (ANOVA) was performed to identify whether the effectiveness of school administrators under three parameters vary with regard to the service period based on the views of teachers; and t-test whether vary with regard to their genders. Pursuant to the research findings, the effectiveness levels under the culture of school and climate was found as 3.86 as the highest and 3.80 as the lowest for their effectiveness levels during the educational leadership. Consequently, the managerial effectiveness skills of school administrators were found at sufficient levels.