The notion of inclusion is not a simple matter to define. It will mean different things to different people at different occasions. In school, inclusive education, may relate to a democratic view, meaning that all students should have the same opportunities and rights to participate in the mainstream educational schooling, on equal terms. In the current school political debate, the term “inclusive education” has gained a significant position and can relate to students’ grades in school subjects. The awareness of inclusion partly comes from critical reflections about how schools are handling the diversity amongst students. This thesis is part of a national research and school improvement program dealing with inclusive learning environments for students in the compulsory school. The aim of the study is to contribute with knowledge concerning teachers’ conceptions about lesson planning and teaching from a student inclusive perspective. Focus is on teachers’ perceptions of the multifaceted teaching in heterogeneous classes where the diverse qualifications of the students bring different challenges. The study contains two empirical investigations. The first one has a quantitative methodological approach, using a web-based questionnaire directed to all teachers, whose schools take part in the national program. The second study has a qualitative research design and the empirical data contains a case study with informants from three schools that also participated in the program. The theoretical analysis, based in a pragmatic understanding, is performed through Biesta’s dimensions of the aim of education; Uljens’ model for analyzing didactic action, Hedegaard-Sørensen’s approach on situated professionalism and Tomlinson’s perspective on differentiation of teaching as a basic pedagogical principle. The results show that teachers hold a positive attitude to the idea of inclusion. Mediating knowledge, in an inclusive teaching context, is regarded as an important but also as a difficult task to carry through during lessons. The teachers experience a dilemma when teaching-balance is requested between single students’ needs and the interest of the class as a whole. Differentiated teaching, taking into consideration the students’ diverse ways of learning, is conceived as an important aspect from a student inclusive perspective. The results also show that collegial collaboration, before as a well as during and after completed lessons, is regarded as a valuable aspect for the inclusive didactic lesson planning and lesson work to be successful.