This integrative study builds on the established theories of public policy analysis, economics, and public finance by empirically investigating and analyzing the determinants of public expenditure on education in Thailand. For the purposes of this study, it is posited that education expenditures are determined by multidimensional factors. A number of economic-demographic, political, institutional, and decision-making theories are therefore examined, together with the concept of education. This study recognizes and quantifies education expenditure by both types and stages of education according to the allocation of government budget and the education system in Thailand. The results reveal that education financing policy in Thailand is mainly determined by last year's expenditures. Industrialization also increases the total education expenditure. This is what the incrementalism theory and Wagner's Law postulate, respectively. Moreover, unemployment has an inverse impact on several types of education expenditures. The results imply that the Thai government mainly takes into account only certain factors and neglects to incorporate the importance of demographic and educational indicators when allocating education expenditures.