In the educational sphere, the concept of "democracy" is used in many and varied ways, though the hegemonic school culture often starts from a concept of democracy that is taken for granted, and it is understood that the entire educational community shares a similar concept. As a result of the research project "Democracy, participation and inclusive education in schools" (EDU2012-39556-C02-01/02) we realized that the above-mentioned concept is used without being accurately defined in the school setting. This observation is what has prompted us to write this article, basically structured in two parts. In the first part, based on the theoretical debate occurring in the field of social sciences, we delimit the concept of democracy and structure it in four basic dimensions: governance, inhabitance, otherness and "ethos". In the second part, we specify and examine in depth these four dimensions in the school setting in order to construct a broad and transversal, yet specific, definition, with which to be able to develop ambitious democratic projects and, in turn, contribute to scientific debate.