The aim of this study is to investigate the academic success, self-efficacy and psychological resilience of sixth-grade students who started primary school in different age groups and who were followed up longitudinally. The study group of this research consisted of a total of 485 students, 73 of whom were longitudinally trained in the sixth grade, on the Anatolian side of Istanbul. In order to collect quantitative data of the research, Child and Young Psychological Resilience Scale, Self-Efficacy Scale for Children, Mathematics Performance Test, and Turkish Performance Test were used. Qualitative data were collected through sentence Completion Form created by the researchers. Kruskal Wallis H Test was performed in order to analyse whether independent variables differed according to age, while the students' first class memories were investigated by the content analysis, and the data were categorized and divided into themes. Results showed that the academic achievements, self-efficacy and psychological resilience of both the students who were followed up longitudinally and those of the whole study group did not differ significantly in terms of the age of starting primary school. According to the qualitative findings of the students' memories of the day they started primary school, it was observed that the students who started primary school at a young age used more negative expressions about their first days at school. The results obtained are discussed within the framework of the related literature.