The purpose of this study was to examine principals’ effectiveness in team building andrnleadership in secondary schools in Yeka sub city, Addis Ababa. The researcher employedrnquantitative research approach that includes correlation and descriptive survey researchrndesigns. The size of the population was186 teachers, 28 principals and 7 supervisors of thesern176 teachers, 28 principals and 7 supervisors were included in the sample making a total of 211rnsamples. And the remaining 45 teachers and 4 principals are left for pilot study. In selection ofrnprincipals and teachers as sample of the study, comprehensive sampling technique and randomrnsampling were used respectively. Comprehensive sampling technique was used for Supervisorsrnalso. Closed ended questionnaire and interview were instruments used for data collecting.rnQuestionnaire was prepared and employed to measure the understanding of teachers andrnprincipals about the effectiveness of principals in team building and leadership. Pilot study wasrnconducted before the questionnaire was distributed to respondents. The reliability of therncommonly practiced team leadership and team and team building practice scales ofrnparticipatory, transformational and transactional was determined by Cronbach’s Alpharncoefficient. The coefficients of reliability were 0.76, 0.74 and 0.71 respectively. 204rnquestionnaires were properly filled in and analyzed. Results fromteachers’response showed thatrnprincipals use participatory leadership in team building and management practices. There wasrnsignificant difference on the perception of principals and teachers on effectiveness of principalsrnon team leadership practiced in secondary schools of Yeka sub city, Addis Ababa. Therefore thernresearcher concluded that principals in Yeka Sub city,Addis Ababa were partially effective inrnteam building and leadership. The sub city and woreda’s responsible body need to support them,rnsupervisors helpmate and trainings given by colleges are some of the recommendations