The present study aims to investigate differences between a sample of bilingual primary school pupils according to their gender and socioeconomic and cultural level, based on their mental executive functions (EFs) abilities on one hand, and bilingual cognitive flexibility (BCF) on the other among a sample of bilingual primary school pupils, aged between (9-12) representing the late childhood phase, who speak both Arabic and English. Furthermore, the study target shedding light on the relationship between bilingual cognitive flexibility and mental executive functions among primary school pupils (9-12) years old. The study followed the descriptive approach. The descriptive diagnostic sample was randomly chosen. The final N=(136)of primary middle school pupils. The measurements to diagnose the dynamic variables were: The Executive Skills Questionnaire (ESQ) - Dawson and Guaref, for children (36 items), translated by the researcher, for Bilingual Cognitive Flexibility, the researcher prepared a scale. As for the socioeconomic and cultural level, the researcher presented a form. Dealing with the statistical methods, the researcher used T-test for independent variables, one-way ANOVA, Tukey's test, and the Pearson correlation coefficient method. The results of the study revealed statistically significant differences between the demographic variables (gender-socioeconomic and cultural level), and the dynamic variable (Cognitive Bilingual Flexibility). There were no statistically significant differences between the demographic variables (gender), and the dynamic variable Mental Executive Function, whereas there were statistically significant differences regarding the demographic variables (socioeconomic and cultural level), The result also showed a positive relationship between bilingual cognitive flexibility and mental executive functions in primary school.