This research aims to investigate cittaslow movement, which developed as a result of crises and paradoxes, to open a new movement area and sustainability within the case of Seferihisar. The following question "Does the calm city movement offer a sustainable and alternative understanding of development in the case of Seferihisar in Turkey?" was investigated during the study. The research was conducted on the basis of a mixed methodology. In the scope of the research, in-depth interviews were held with the stakeholder institutions and local actors selected by purposive sampling; the questionnaire was applied face to face to 332 individuals selected by proportional stratified sampling from local people. Both qualitative and quantitative data were integrated during processing from the Neo-Marxist approach. As a result of the research, the services of the municipality increased, crucial improvement was provided in terms of sustainable development by the projects with the cittaslow title; however, with the increasing population, a number of problems such as urban sprawl, gentrification, increase in cost, alienation, increase in income differences have arisen. Finally, although the studied case provided good practices, there are obstacles in the sustainability of the cittaslow movement in the context of the case studied.