Studies focus on the importance of developing decision-making skills, which are among thinking skills, at early ages and highlight that these skills, if not developed at early ages, lead to some problems at the later stages of individuals' lives. Curricula on the level of primary school in Turkey, based on their visions, aim to train individuals with decision-making skills. In reaching this objective, it is important to determine what type of problems are experienced in the process, to what extent objectives can be reached and what the factors that affect the process are. With this mixed method study, it was aimed to examine the problems experienced in and the existing situation of development of decision-making skills. The design of the study was adopted as the convergent parallel design. The participants of the study consisted of 9 teachers who served as 4th grade teachers and 543 4th grade students from different socioeconomic levels. As the data collection instruments, the study utilized a "Student Personal Information Form", the "Decision-Making Skills Scale", "Decision Rules Implementation Test", "Choices and Outcomes Activity" and semi-structured interviews developed by the researcher. The results of the study showed that the teachers needed information and guidance in terms of teaching decision-making, they experienced problems related to the curricula and families in the process, and approximately half of the students had difficulties in terms of defining-expressing decision-related problems. Additionally, in teaching decision-making, problems based on the teacher, the curricula and the families were experienced, and these problems had negative effects on the development of the decision-making skills of the students.