Strategic plans are considered to be very important in the management and success of organizations. School strategic planning is key to success of a school with regard to achievement of its mission, goals and objectives. Though the Ministry of Education directed that Public Secondary schools must formulate and implement Strategic Plans; some Schools have been faced with the challenges in the implementation of their strategies. This study carried out an analysis of factors influencing the implementation of Strategic Plans in Public Secondary Schools in Mukurweini & Othaya Sub-counties of Nyeri County, Kenya. The study was guided by four objectives and data was collected to answer the following four questions: - How Managerial skills, Institutional policies, Resources allocation and Rewards & Incentives influence the implementation of Strategic Plans. The population for the study was the institutions Principals or their Deputies in the 2 Sub-counties. The accessible population was made up of 66 schools Principals/Deputies (32 in Mukurweini and 34 in Othaya) and an interviewer administered questionnaire was used. Both descriptive and quantitative was collected and analyzed in order to answer the four questions of the study. The study had 20 schools responding from each sub-county representing 65% in Mukurweini and 60% in Othaya. Based on the findings, it can be concluded that public secondary schools in Mukurweini & Othaya Sub-counties had strategic plans and their implementations are influenced by among other factors, Managerial skills, Institutional policies, Resources allocation and Rewards/Incentives. Its recommended that Principals/Deputies be equipment with the necessary Managerial Skills; schools should enforce institutional policies; should have resources allocation policies/budgets and should have reward/incentive schemes which help in the successful implementation of the school?s strategic plans. Key Words: Strategy, Implementation, Public Schools, Kenya.