This research was conducted to examine master's and doctoral theses that address the concept of numbers in preschool mathematics education in Turkey by considering various variables such as level, year, participants, data collection tools, data analysis methods, and the similarities or differences among theses with similar objectives. The study adopted a systematic literature review approach, and document analysis was employed as the data analysis method. The majority of the graduate theses included in this study were written between 2016 and 2020 at Gazi University. The study group of the theses primarily consists of preschool children, with the age distribution being children aged 60 to 72 months. While quantitative research methods are mostly used in the examined theses, a correlational design is preferred as the research design. Descriptive tests have been predominantly used as the data collection tool. The most commonly preferred data analysis method in postgraduate theses is the t-test. It has been observed that there are 12 theses included in the research that were written with similar purposes.