The chapter deals with the teachers' experience of transition between primary and lower secondary school. The aim of this chapter is to systematically summarize and interpret the individual interviews with class teachers from the fifth and sixth grades of the basic school. Based on the experience they are able to describe the pros and cons which come with the transition of students between primary and lower secondary stage of basic school. During our research we focus on the determination of these research questions (1) what comes with the transition between two stages (2) how it is important for teachers and the school management to prepare their students for the transition (3) how students perceive the transition from the teachers' point of view (4) how teachers perceive the departure of students into multi - year gymnasia and other selective schools (5) how teachers solve the problems which occur with admission of new students into the sixth grade of primary school (6) how the class climate can change after the ending of primary school education. Based on the analysis of literature, we chose a qualitative research approach. Its advantage is that it allows to understand in detail the observed phenomena and to obtain detailed information about it. We made interviews with teachers from the deliberately selected schools who expressed what the transition between two stages in the Czech educational system means for them.