Level of economic development has been found to be among the strongest determinants of corruption level in cross-country studies. Those studies use income per capita as a measure of level of development and found that higher level of corruption is associated with lower level of income. We argue that, at any given income level, education is also a very important determinant of the level of corruption and failing to include education may bias or over-estimate the importance of income. We estimated an empirical model of individual’s attitude toward anti-corruption using a large sample of 9,020 individuals that represent Indonesian population and find that the effect of income (proxied by expenditure) is either weakened or eliminated when we control for the level of education. The effect of education is also found to exhibit a non-linear pattern which implies that investing in education will have increasing returns in the form of anti-corruption attitude. This finding supports the view that increasing access to education is an effective measure of reducing corruption norms particularly in developing countries.