The research aimed at examining performance-based formative assessment approaches (Processes/Products) via the flipped classroom model and its impact on developing linguistic self-efficacy among Al-Azhar secondary stage students in North Sinai. A quasi-experimental 1×2 factorial design was employed. Independent variable was performance-based formative assessment approaches included two types approaches of performance-based formative assessment presented via flipped classroom model (processes vs. products), dependent variable was linguistic self-efficacy. The participants were 64 students (males) selected from first Secondary grade students by Al-azhar in North Sinai, were assigned to two experimental groups. The first experimental group utilized a performance-based formative assessment approach for processes; included 32 students, the second experimental group utilized performance-based formative assessment approach for Products; included 32 students. The research tool represents linguistic self-efficacy scale. The results revealed that a statistically significant difference at ≤ 0.05 between the mean scores of the two experimental groups in linguistic self-efficacy in favor of performance-based formative assessment approach for products.