Abstract. In the first two parts of this paper we realise a brief context introduction for diversity and proportionality, presenting also some aspects from the relevant related literature. In the third part we provide an analysis using a selection of indicators considered for a group of countries (Germany, France, Poland and Czech Republic). We emphasize the diversity of the banking structures, types and sizes of banks acting in the selected banking sectors under the umbrella of the European banking system. We add also relevant insight and considerations to the analysis, related to the regulatory and supervisory framework, which should accommodate a diverse range of banking structures, addressing also the proportionality principle. The forth part includes findings of our analysis as well as other relevant discussions, related to the impact and complexity of the topics, for policy implementation. The final part includes our concluding remarks.

Keywords: banks, banking model, customer behaviour, regulations, diversity, proportionality principle, economic development.