The objectives of this research were 1) to examine the causal relationship model of factors affecting the effectiveness of primary schools which was developed through empirical data, 2) to study the factors that have direct, indirect and overall influence on the effectiveness of primary schools in Khon Kaen. The samples were 640 school administrators including teachers in Khon Kaen primary schools. The data were analyzed by program computer using the method of structural equation modeling (SEM). The research results indicated that the causal relationship model factors affecting the effectiveness of Khon Kaen primary schools consist of 5 latent variables or factors namely: 1) school vision, 2) academic leadership, 3) promotion of school climate and environment, 4) quality teaching, and 5) learned behavior of students. As for causal relationship model of factors affecting the effectiveness of the above-stated schools, it is found that the construct validity is in congruence with the empirical data. The indices of congruence are Chi-Square at 94.793, df = 87, P-value=0.2662, TLI= 0.998, CFI=0.999, SRMR=0.031, RMSEA=0.013, with statistical significance at 0.01. The factors that directly and positively affect were of statistical significance at 0.01, are 1) shared vision, 2) academic leadership, 3) teaching quality, respectively, The most indirect influential factors affecting the school effectiveness are 1) shared vision, having indirect influence in positive manner to climate and environment of the schools, affecting in positive manner to teachers' teaching quality, and 3) academic leadership having indirect influence in positive manner on school climate and environment that affect students' learning, respectively.