As a result of socio-economic transformations in recent years, an increasing number of new social risks and an increasing number of people in need are emerging. Sometimes, existing solutions are not enough so we have to find new ways to solve the problems we face. One of these ways is to develop social innovation. Social innovations are new ideas, products and services that meet a social need. They are cited as indications of a new rethinking of the sustainability of social policies, aimed at ensuring social and environmentally sustainable growth, better jobs and a higher quality of life. Social innovations erase national and sectoral boundaries and respond to new social risks that arise. Europe's success depends on its ability to innovate. Innovation is at the heart of the new Europe 2020 strategy and is the best way to successfully tackle economic and social problems. With Croatia's accession to the European Union, social innovations are gaining in importance, but they are facing a number of problems. In order to better understanding what social innovation is, what is the role and mechanisms of the European Union in the field of their development, in this paper we have defined the concept of social innovation, its typology, we have described social innovation in different sectors, we defined the concept of the European Union, its characteristics , public policies and mechanisms, and we have described in detail the role and importance of the European Union in fostering social innovation.