The main objective of the article was to develop a concept for measuring local sustainable development and to identify and assess its level using the example of counties in the Masovian Voivodeship. The paper consists of a theoretical and empirical part. The theoretical part reviews the literature on sustainable development, while the empirical part presents the level and changes in sustainable development of the surveyed counties. Taking into account three development components: economic, social and ecological, the level and changes were estimated for them, as well as the degree of sustainability between them. The research covered 42 counties in the Masovian Voivodeship in 2006 and 2018. The main source of data was the Central Statistical Office Local Data Bank. The research used 35 primary variables. The main research methods were factor analysis and the ranking method. The obtained results indicate that the highest level of sustainable development occurred in the rural counties of the central part of the Masovian Voivodeship located up to 70 km from Warsaw, and the lowest - in the rural counties located in the eastern and southern parts of the Masovian Voivodeship.