The article addresses the issue of the role and significance of the development intensity index in spatial planning, which allows for controlling the density of development in cities. The aim of the article is to assess the possibilities and justification for using existing provisions in local spatial development plans regarding the permissible development intensity in the general plan, with particular emphasis on its role in shaping urban space, sustainable development and the quality of life of residents. The city of Szczecin was assumed as the research area. The article discusses the definition of the development intensity index and its application in spatial planning. The urban tissue in selected parts of Szczecin was described and its actual density was analyzed. A comparative analysis of the provisions regarding the development intensity in local spatial development plans was carried out on the example of planning documents prepared for the city of Szczecin. The research results from the provisions in selected local spatial development plans and the draft general plan of the city of Szczecin, which is being developed, were compiled and illustrated. Additionally, reference was made to the amendment to the Act of 27 March 2003 on spatial planning and development, and in particular to the institution of the general plan, which is of key importance in determining the principles of spatial development of the city.