The purpose of the study was to assess the practice of instructional leadership behavior and its contribution to school climate in secondary schools in Mekdela Woreda South Wollo. In order to meet the objectives of the study, descriptive survey method was employed. Data was gathered from 162 teachers and from 28 instructional leaders which includes principals, a supervisor, vice principals teachers' developmental groups who were selected by comprehensive sampling method. The data were collected using pre­ tested close ended questionnaires. The quantitative data were analyzed by descriptive , statistics such as mean and standard deviation and inferential statistics such as one sample t -test, Pearson's product moment correlation were carried out to analyze the collected data. According to the analyzed data, school principals and delegated staffs were found at low performance in defining school mission, managing curriculum & instruction, ilpervising instruction and monitoring instructional program. It was also identified that the behaviors of school principals and delegated staffs were below average in supportive behavior, directive behavior, engaged behavior, frustrated behavior and it was in low in creating intimacy with the teachers . As a result, the climate of the schools was nearly closed. On the other hand, a positive and significant relation was observed between the performance of instructional leadership behaviors and school climate. Furthermore, the data showed .that except monitoring instructional program behavior, there was no other instructional leadership behavior that contributes to ' apparent school climate in the study area. The climate of the school was the composite of all instructional leadership practice. School leaders needs t? work in collaboration with teachers, community and other officials in order to make a good school climate for the achievement of students. Moreover, the school instructional leadership should focus on empowering teachers; mission and vision attainment by setting high and achievable standards, shared leadership in order to improve the teaching and learning outcomes