The downward trend in the academic achievement of public secondary schools’ students in Oyo State has been a subject of debate among stakeholders in recent times. This study investigated school based management committee system, principal leadership style, effective communication system and public secondary schools’ students’ academic achievement in Oyo State. The study adopted the descriptive survey research design. The study population consisted of all students in public secondary schools in Oyo State. Multistage sampling techniques were employed to select 180 respondents, constituting the study’s sample. Three hypotheses were formulated at 0.05 level of significance to achieve the objectives of the study. Data were collected using four instruments: School Based Management Committee System Questionnaire (r = 0.82), Principal Leadership Style Questionnaire (r = 0.74), Effective Communication System Questionnaire (r = 0.81) and Student Achievement Test. The instruments were subjected to thorough scrutiny by experts in measurement and evaluation to establish the face validity. Pearson Product Moment Correlation and Multiple Regression Analysis were utilised to assess the null hypotheses at significance level of 0.05. The study found out that there was significant positive relationship among school based management committee system, leadership style of the principal, effective communication system and public secondary schools’ students’ academic achievement (school based management committee system, r = 0.78, p<0.05, principal leadership style, r = 0.67, p<0.05, and effective communication system, r = 0.59, p<0.05). The result showed that school based management committee system, principal leadership style and effective communication system jointly contributed to public secondary schools students’ academic achievement (F(2,168) = 16.17, p<0.05). Also, it is indicated that school based management committee system (β = 5.186; T = 3.216), principal leadership style (β = 3.846; T = 2.314; p<0.05) and effective communication system (β = 2.421; T = 1.832; p<0.05) relatively contributed to public secondary schools’ students’ academic achievement, while SBMCS had the highest potency. The research acknowledges the importance of these elements in molding the educational landscape and their capacity to influence students’ academic performance
Keywords: Students’ Academic Achievement, effective communication system, principal leadership style, school based management committee system
