The concept of sustainable development has a number of definitions. In a general sense, it as- sumes interdependence and equivalence of three domains of reality: environment, society and economy. Harmonisation of the relationship between the society, the economy and the natu- ral environment requires the development of new, more efficient and environmentally-friendly technologies, limiting the exploitation of natural resources, energy consumption, the elimination of environment-polluting forms of production, as well as a widespread change of the way of life and revision of the acceptable hierarchy of values. According to the valid principles, the invest- ment trends in municipalities should be in line with the domains of sustainable development, thereby providing balance in all the three areas of investment: environmental, economic and so- cial. The aim of the study is to conduct a comparative analysis of the investment projects carried out in the period of 2007–2013 in selected municipalities of the Warmia and Mazury Region for their compliance with the principles of sustainable development of rural areas. Investment pro- jects co-financed from EU funds were examined. This has allowed us to highlight the spheres of investment, which drew particular attention within the period of time under study. The shifted focus of investment efforts also testifies to backwardness in the supported sphere.