peer reviewed ; Aiming to further our knowledge about what is meant by inclusion, we examined how various conceptualisations relate to people’s attitudes about inclusive education. We assign the varying characterisations of inclusion of specific groups with differing involvement in the education system in Luxembourg, applying the influential systematisation of definitions of inclusion by Göransson and Nilholm (2014). Results of study 1 showed that members of the general population, pre-service and in-service teachers perceive inclusive education in importantly different ways. Although results showed relatively positive attitudes toward inclusive education for the whole sample, attitudes varied by group and in relation to the differential categorisation of definitions. As teachers’ attitudes and the extent to which they feel prepared to implement inclusive practice are crucial for the success of inclusive education, the latter aspect is further investigated in study 2. Results showed that teachers with more in-depth understanding of inclusive education reported more positive attitudes and felt better prepared to implement inclusive practices. Implications for education systems and society are discussed.