The development of critical thinking is conditioned by the action of many factors. To highlight this fact, I have focused on the opportunities offered by textbooks, teachers and learning activities for the development of the critical thinking of primary school pupils in Kosovo. The study begins from the idea that recognizing these opportunities opens the way for further improvement. The study was conducted with the participation of teachers and students. The textbooks of the primary school in Kosovo were also studied. The study has descriptive and mixed nature. His descriptive character is related to the description of the possibilities for the critical thinking development in the primary school, and the mixed character of methodology is related to the mixed nature of the collected data: textual facts, teachers’ opinions, learning practice / activities. The design of this research was conducted by combining three main methods: content analysis, interview and observation, by comparing each-other’s results of content analysis (tabs), teacher’s interviews, and observation in classes. This was done by analyzing the content of 24 textbooks (Literary anthology 1-5, Albanian Language 1-5, Civic Education 3-5, History 5, Art 1-5 and Music 1-5), 336 teachers were also interviewed and 336 lessons were observed. To collect data from the textbooks, an internationally recognized instrument for critical thinking has been modified, which is then adapted for the construction of an interview guide as well as for observing classroom activities. The study’s findings are interesting and important: it is noted that: the texts contain considerable opportunities for developing critical thinking, teachers have positive attitudes and classroom activities have useful elements that contribute to the development of critical thinking. Also, there are some differences from text to text, from teacher to teacher, and from one lesson to another. The study conclusions are descriptive and show which texts, opinions, and activities develop more critical thinking and which ones need further review and improvement. We come to some useful conclusions for both curriculum compilers (authors and publishers), their implementers, and inspectors.