The objective of this study was to assess the principal's leadership effectiveness in rnimplementing school improvement programs in secondary schools of the Wolaita rnzone. In this study descriptive survey design was used with quantitative and rnqualitative methods. Among the 60 public secondary schools found in the wolaita rnzone .10 was taken as a sample by using random sampling techniques. The sample rnteachers 175 (50%) were selected by using simple random sampling techniques. rnAdditionally, 30 public secondary schools head and vice principals, supervisors, 4 rnSIP directorates were selected by available sampling techniques. Finally, 10 student rnrepresentatives, 10 Kebele Education and Training Board (KETB) representatives, rnand PTA representatives were included by using purposive sampling techniques. The rninstruments of data collection were questionnaires, interviews, focus group rndiscussion, and document analysis. The data were analyzed by using mean, average rnmean and standard deviation. The data gathered through open-ended questions, rninterviews, and document analyses were analyzed qualitatively through narration. rnThe findings of the study indicated low performance of secondary school principals in rnimplementing school improvement programs.rnRegarding leadership roles used by school principals implementing SIP; the class rnobservation to support teachers and make agreement with the teachers and the rndepartment heads the result indicated the secondary school principals were not rneffective, as the finding of study revealed the principals monitoring students for rnleadership effectiveness is ineffective. Regarding the relationship between leadership rnroles and principals effectiveness in implementing SIP; relationship between the rnsecondary school principals leadership effectiveness and with provision of rninstructional materials, curriculum monitoring, creating conducive environment, rnobserve classroom practice, and improvement of stakeholders participation Pearsonâ€™s rnr parametric test correlation revealed that there is a significant and positive rnrelationship between principals effectiveness and students performance. Regarding rnchallenges teachers are not attending lesson plans, lack of budget, lack of rnstakeholders participation, inadequate numbers of trained human resource, students rnindiscipline, limitation of textbooks, inadequate science laboratories, work load, lack rnof parents commitment in school were some of the challenges of secondary school rnprincipals in implementing school improvement programs. In general, as the finding rnof the study revealed secondary school principals leadership effectiveness in rnimplementing SIP of the study areas were ineffective. rnTherefore, it is recommended that,to improve instructional material problem, thernprincipals and oher stakeholders were developing projects to fillfull teaching rnmaterials. To solve inadequate human resource, REO & ZED should employ rnavailable trained teachers and principals. Woreda Education Offices making rncooperation with the school principals need to improve community involvement. rnFinally, the school principals and supervisors are advised to mobilize communities rnand other stakeholders to improve SIP.