The article is devoted to an analysis of two aspects addressed in the title: monopoly control in the economy, being source of losses due to non-optimal allocation of resources and social costs on account of growing inequality of income distribution, as well as monopoly control in politics, resulting in control over state institutions exercised by narrow pressure groups, at the expense of interests of the rest of the society. The author proves that unfavourable socio-economic developments in Poland are not the consequence of marketisation of the Polish economy but they result from underdevelopment of the market taken as free competition in all areas of social life. This underdevelopment is caused by excessive and improper state intervention hampering the expansion of institutions indispensable for effective functioning of the market, in order to redistribute incomes to the benefit of narrow interest groups at the expense of the rest of the society. Monopolies in the economic sphere in Poland are a function of monopoly in the political sphere, representing interests of groups holding control over state authority institutions. That system generates huge social losses reflected in a slowdown of economic growth and in mounting social inequalities which may endanger the State’s stability.