Researchers argue that students need to understand the language and the key concepts of each discipline to understand the academic content. The purpose of this study is to develop, analyze and evaluate a development project in civics. Therefore, the study answer following questions:  How do subject-specific concepts take place during the lessons according to the students? In what way can concept definition maps encourage students to talk about subject -specific concepts? How do students experience the work with concept definition maps? Two qualitative methods are used to answer the questions, both interviews and classroom observations. The interviews focus on how the students describe their experience with subject-specific concepts during civics lessons but also how they experience the work with concept definition maps which was implemented during the intervention. The observations onthe other hand show in what way the concept definition maps encourage students to talk about subject-specific concepts. The theoretical framework of the study is based on the sociocultural perspective and other theories that stress the importance of encouraging students to generate their own meaning of terms but also how the language develops in interaction with others.The result shows that the students often rely on the definition they get from their teacher orthe textbook but there is no room for students to explore the concepts themselves. All the students felt that the concept definition maps had good impact on their understanding of the subject-specific concepts. The results also showed that the there was a positive interdependence during the intervention where the students learned from each other’s prior knowledge and paths of thinking.