The main purpose of this study was to investigate the Principals’ leadershipeffectivenessrningovernment secondary schools of Silte zone. In this study descriptive survey design was usedrnwith both quantitative and qualitative methods of data analysis. In this Zone there are 15rnworedas; among these 6 were selected using simple random sampling techniques. For this studyrntotal populations size and total sample size were 250 and 219 respondents respectively. Of therntotal sample size of the four groups were involving 98 teachers, 85school leaders, 6 supervisorsrnand 30 PTSAs as sources of information from the six selected secondary schools. The samplingrntechniques employed were stratified random sampling for teachers; available samplingrntechniques for school leaders, supervisors and PTSAs. The collected data through closedrnquestions were analyzed using descriptive statistical tools as frequency percentages, mean,rnweighted mean and the inferential statistics t-test was employed to analyze the data obtained.rnThe data gathered through open- ended questions, interviews, FGD and document analysis werernanalyzed qualitatively through narration for the purpose of triangulation. Qualitative data werernanalyzed after the responses were transcribed using respondents’ own words and categorized inrnto various themes and subthemes. The findings of the study indicated that the effectiveness ofrnschools principals’, in setting goals, developing vision, forming strong functional relationshiprnamong the school community, and showing professional endeavors in inspiring teachers do theirrnwork enthusiastically was below the desired level. The study further revealed that lack ofrnadequate training and experience related to the functions of instructional leadership, lack ofrnvision, problem related to instructional staff and decision making on routine works that had lessrnvalue to the schools’ vision and mission were some of the main problem hindering principals’rnleadership effectiveness. Accordingly, it is concluded that almost all of the school principalsrnwere not effective leading core activities of their schools by forming communal cooperationrnamong the staff within the school, on the one hand, and collaboration between the staff of thernschools and the community outside the schools, on the other hand. Finally, it is recommendedrnthat responsible parties including Silte zone Education office are advised to fill the knowledgernand skill gaps of the principals by designing and providing long and short term professionalrntraining and development programs on: strategic instructional leadership, effective cooperativernand collaborative school leadership styles as well as internalization of the selection criteria asrnstipulated in “A Blue Print for Teachers Development Program†in a suitable manner