This article contains an analysis of the “ECC effect,” that is, the long-term change produced in Polish cities by participation in the competition for European Capital of Culture 2016, which lasted in Poland from 2007 to 2011. The authors concentrate on four basic subjects: (1) city identities; (2) city images; (3) the influence of new cultural institutions on the socio-cultural fabric of cities; and (4) the development of cultural policies and the Europeanization of Polish cities. Their findings are based on the research project “The ECC Effect: In Search of New Urban Narratives,” which was commissioned by the IMPART Festival Office and conducted in 2016 in 7 of the 11 candidate cities: Gdańsk, Katowice, Lublin, Łódź, Poznań, Szczecin, and Wrocław. The authors claim that the competition for European Capital of Culture indubitably initiated extensive transformation processes in Polish cities. It led to an improvement in their images more openness and internationalization, and to a redefinition of the role of culture in innovative development policies.