Sustainable urban development is one of the key areas of development policy in Poland, which is in line with global trends. Sustainable urban development requires an integrated approach that takes into account the complexity and dynamics of phenomena and processes taking place in the urban environment. Meeting the challenges of urban development requires, on the one hand, a steady increase in the capacity of cities to plan and implement development projects, and on the other hand, a favorable regulatory and financial framework and support instruments that are an adequate response to the needs of urban centers. The Cities' Partnership Initiative (CPI) is a flagship project of the Ministry of Development Funds and Regional Policy of Poland (MDFRP) aimed at supporting sustainable urban development. This final report is the third product of the Reimbursable Advisory Service Agreement on Sustainable Urban Development - Cities' Partnership Initiative concluded between the MDFRP and the World Bank on January 28, 2022. The report summarizes the project work, including the results of the work of 30 CPI-participating cities, and presents conclusions and recommendations on the three thematic networks and the CPI formula itself.