Small towns around the world contribute to sustainable development at the regional, national and international level, and play an important role in human settlement networks. They can create cooperation networks to increase their competitive advantage relative to large cities and to promote regional growth. Organizations that provide a shared platform for mutual assistance, cooperation, exchange of experiences and the implementation of measures for resolving socio-economic problems can increase small towns' growth potential and promote the achievement of common goals. One of such organizations is the International Cittaslow Network which brings together small towns willing to implement the Slow City philosophy. The aim of this study was to classify the member towns of the Polish Cittaslow Network based on their socio-economic development and to identify the opportunities that arise from Cittaslow membership. It was also the authors' intention to present and popularize the Wrocław taxonomic method in the international arena. The results of the study indicate that members of the Polish Cittaslow Network differ considerably in socio-economic development, growth potential and barriers to development. However, the socio-economic status of most towns has improved. The study demonstrated that small towns can benefit from joining cooperation networks at the national and international level. •The taxonomic method for evaluating the Polish Cittaslow Network was implemented.•The benefits of Cittaslow membership were presented.•The Wrocław taxonomic method supports analyses of towns' development potential.•The analyzed towns differed in their levels of socio-economic development.•The results offer valuable insights for towns that aspire to become Cittaslow members.