This paper examines the quality of Hong Kong's sub-degree level education provided by the self-financing institutes in terms of its impact on the earnings of workers, based on Hong Kong's 2006 by-census data. Education is an investment in human capital that enhances the productivity of workers and increases their lifetime incomes; and a more productive investment will produce a higher rate of return. The effects of education on workers' earnings can be regarded as a proxy for measuring the quality of education undertaken. This study shows that, as regards earnings, and therefore (indirectly) quality, the quality of sub-degree level education provided by some self-financing institutes is statistically significantly lower than that provided by publicly-funded institutes. (Contains 1 table and 1 note.)