In Kenya, school development planning for public schools involves determining school needs, prioritizing school needs, preparing action plans, implementing and monitoring the plans. Specifically, public schools in Mbeere -North sub-county have always adopted strategic plans as directed by the Ministry of Education. However, schools continue experiencing dismal performance and poor management. Thus, the study assessed the influence of school dynamics in the implementation of strategic plans in public secondary schools in Mbeere North Sub- County, Embu County. The study was guided by two research questions; 1. What is the influence of stakeholder involvement on the implementation of strategic planning? 2. How does the principal’s leadership influence the implementation of strategic planning? The study adopted a mixed method approach with an explanatory sequential research design. The study used stratified sampling to select 341 respondents. Questionnaires were used to collect data from Board of Management members, teachers and students whereas interview guides were used to collect data from principals, the Sub-County Director of Education and the Quality Assurance Officer. Validity was established through expert judgement. Reliability was determined using test-retest technique. Qualitative data was analyzed thematically while quantitative data analyzed using descriptive statistics. The study found that secondary schools in Mbeere North Sub- County had long term strategic planning, which if properly implemented, would benefit the stakeholders in schools. The study established that some principals included the stakeholders in the implementation of strategic planning. The study found that effective leadership in strategic planning play the role of making good planning, providing better awareness of needs