What explains the spectacular increases in inequality of disposable income in transitional economies of Central and Eastern Europe? There are at least two possible explanations. First, the pre-tax distribution of income became more unequal because of the shift to a market economy. Second, the degree of progressivity of the income tax system declined. But each of these factors is in turn determined by other structural changes associated with transition-notably, the decrease in public provision of key public goods, the decrease in non income tax revenue sources such as profits from public production, and perhaps a decline in society's inequality aversion. This paper develops a framework in which these different forces on inequality can be assessed. Using a simple two-type and two-sector optimal income tax model with endogenous wages, we first of all show that a decrease in the provision of public goods could indeed lead to increasing "inherent" inequality, in other words inequality in market incomes. It then deploys the Mirrlees model of optimal non- linear taxation to assess the relative impacts of this increase in inherent inequality, the decreasing sources of non income tax revenue, and possible declines in inequality aversion; to get a numerical feel for their possible impacts on inequality.