BackgroundComputational thinking (CT) has emerged as a critical component of 21st‐century skills, and increasing effort was seen in exploring the development of CT skills in K–12 students. Despite cumulative research on exploring students' CT acquisition and its influencing factors, learners' development of the skill over time and the underlying mechanism that contributes to individual differences remain unclear.ObjectiveTo bridge this gap, the present study aimed to explore the individual differences in CT acquisition among primary school students and how these differences were shaped over time. Specifically, variations in the development of CT across demographics, including gender and learning experience, were explored.MethodThree waves of data were collected from a sample of 322 primary school students (aged 7–12) across 18 months, with a 9‐month interval between adjacent waves. A time‐lagged model was leveraged for data analysis, and control variables were included in the model to strengthen statistical robustness.Results and ConclusionThe results indicate that male students and those who were more experienced in coding tended to have more positive attitudes toward coding. Additionally, coding interest was found to mediate the relationship between demographics and CT, demonstrating that male students and more experienced learners tended to be more interested in coding, which, in turn, contributed to the development of CT skills in later stages.ConclusionThe study provides valuable insights into the mechanisms underlying individual differences in CT development over time. The findings highlight the importance of nurturing coding interest among female students and promoting coding exposure for novice learners.