This thesis deals with research on the implementation of corporate social responsibility (CSR) in small and large enterprises in Croatia. The structure of work is formed in seven chapters. First, the notion of corporate social responsibiliy (CSR), phenomena, models and the implementation strategy is explained. Subsequently, there is a chapter on the necessity of introducing the concept of corporate social responsibility, its advantages, participants and drivers. Furthermore, guidelines for introducing CSR in business and the ways of measuring it are listed. Particular emphasis is placed on the chapter on analyzing the state of socially responsible business on the implementation of the concept in the Republic of Croatia. The chapter mentions its development, primary and secondary stakeholders, and examples of four small and three large companies whose focus is to make profit in a socially responsible and acceptable manner. Based on the above examples, this study presents the differences in procedures and methods of social responsibility in relation to the size of the enterprise but also the ownership structure (most of the above mentioned companies are privately owned by Croatian entrepreneurs while only one listed state-owned enterprise). Secondary sources have been used for collecting and analysing data in this paper. Most of the data was gathered through the professional literature found in libraries. The Internet was used for searching professional articles, publications, and also gathering data about small and large businesses. Due to the variety and plurality of the literature used, interesting conclusions were drawn about the implementation of the corporate social responsibility in small and large companies. The aim of the thesis is to draw attention to the benefits of the corporate social responsibility and to establish the difference between corporate social responsibility of small and large enterprises in Croatia.