The current research paper investigates the impact of McCarthy's 4MAT model on developing writing skills among upper-grade primary pupils.  Sixty-four pupils in six primary-stage grades were chosen as the study participants and were divided randomly into two matched groups (a control group and an experimental one).  The researcher adopted the two-group quasi-experimental design. The experimental group 32 pupils from Omar Bin Abdaliz primary school in the Assuit regime, and the control group 32 pupils from Al-Zaher primary school in the Assuit regime in the second term of school year 2023-2024. The writing test with the scoring rubric was administered to the participants of both study groups to assess pupils' development in the specified writing skills before and after the experimental treatment. The data collection process included both quantitative and qualitative techniques. The researcher used statistical methods to analyze data, including the mean, standard deviations, and effect size.  The study's results confirmed statistically significant changes, favoring the experimental group's post-testing at the 0.01 level. Thus, these results provide evidence of the educational value of integrating McCarthy's 4MAT model with the content of the curriculum. Future researchers could focus on integrating learning style applications in light of the 4MAT model into developing other skills.