The most important objectives of the Common Agricultural Policy include the need to increase the efficiency of agricultural production by promoting technological progress, rational development of agricultural production and optimal use of means of production in agriculture. These activities are to lead to ensuring an appropriate standard of living for the population living in rural areas by increasing the income of people employed in agriculture, and thus to the gradual development of villages, agriculture and rural areas. One of the methods of optimal use of means of production in agriculture is to exclude land of marginal importance for agriculture from agricultural production. Afforestation of agricultural land is, in turn, one of the methods of developing land of marginal importance for agriculture and at the same time a basic means of achieving the objectives specified in the National Programme for Increasing Afforestation, the assumption of which is to increase the forest cover in Poland and at the same time optimal use of land resources in relation to the complex and at the same time heterogeneous needs and possibilities of individual regions of the country. The aim of the conducted research was to diagnose the spatial distribution of afforestation works carried out in the period 2004–2013, which are the basis for recognising changes in Polish forest resources, their ownership structure and regional differentiation. In the analyses, special attention was paid to afforestation carried out on privately owned former agricultural lands with the use of EU CAP financial instruments, available in Poland under the Rural Development Programme 2004–2013, supporting transformations in agriculture and rural areas. The analyses were carried out on the basis of statistical data from the Central Statistical Office on the forest area of ​​municipalities from 2004 and 2013 and a numerical map of afforested lands under the Rural Development Programme 2004–2013.