One of the aims of educational institutions in Turkey is to adopt an understanding of nationalism based on Atatürk's views by students. Atatürk's understanding of nationalism was founded on the unity of culture. It rejects racism. It emphasizes cultural unity rather than blood ties or religious unity. However, various forms of nationalism in Turkey can find supporters. For this reason, it is important to examine how secondary school students understand nationalism and with which concepts they explain it. Qualitative research method was used in this research, which aims to examine how students conceptualize and understand nationalism. Since it is important for the students to express themselves naturally, they were asked to write an essay on nationalism. Student writings were analyzed by content analysis. According to the results obtained within the scope of the study, the students mostly used the expressions "to love homeland and nation" and "to protect homeland and nation" when explaining the concept of nationalism. As the age and grade levels of the students increase, the number of concepts related to nationalism used by students increases. Nationalism is understood differently by male and female students. While female students emphasize the concepts of love and work, male students emphasize the concepts of protecting and independence. Considering the place where the students live, the meaning attributed to the concept of nationalism varies. While the students living in the city center used the concept of love more, the students living in the town focused on the concept of protecting. The most important finding obtained within the scope of the study is that the participants did not base their nationalism on blood ties or religious unity. Students did not use non-inclusive expressions while describing nationalism. For this reason, it was understood that the participants had thoughts compatible with Atatürk's understanding of nationalism.