Tejumoluwa MESAGAN2024-07-312024-07-312023-12Kate TurabianM.EDhttps://repository.lcu.edu.ng/handle/123456789/709The administration of public secondary schools in Oyo State, Nigeria faces numerous challenges that significantly influence the quality of education provided. The study investigated the influence of Staff Development Programmes and Decision-making Styles on the Administrative Effectiveness of Public Secondary School Principals in Oyo State, Nigeria. A descriptive research design was adopted, and the population comprised 11,732 teachers in the public secondary schools (324) in Oyo State, Nigeria. 2,726 respondents were selected with multistage sampling technique. Three research questions were answered, while six hypotheses were tested. A self-developed questionnaire was used for data collection. The results indicated that the principals in Oyo State engage in moderate administrative effectiveness (x̄= 2.68). The most available Staff Development Programme is seminar. Based on the data provided, the frequency, in percentage for the mostly used decision-making styles, it was observed that public secondary school principals tend to adopt directive style most often 39%.The test of hypotheses showed a significant combined influence of decion-making on public secondary school principals' administrative effectiveness in Oyo State (F = 424.310; P < 0.05; R2=0.553). Decision- making styles are predictors of administrative effectiveness. There is a significant combined influence of Staff Development Programmes (F = 274.557, P < 0.05; R2=0.375). Staff Development Programmes predictors have a significant relative influence on administrative effectiveness. There is a significant combined influence of decision-making styles and staff development Programmes on public secondary school principals' administrative effectiveness in Oyo State (F = 539.376, P < 0.05; R2=0.439). Efforts should be made to ensure appropriate decision-making style and staff development Programmes among public secondary school principals in Oyo State. Keywords: Staff Development, Programmes, Decision- making Styles, Administrative Effectiveness Word Count: 265enStaff DevelopmentProgrammesDecision- making StylesAdministrative EffectivenessThesis