This study aimed at exploring causal relationships between two affective factors, self-confidence and positive emotion, and two metacognitive factors, selfreflection and insight components on high school students' mathematics achievement that assessed by formative and summative assessments. The study applied partial least squares based structural equation modeling (PLS-SEM) approach to test the path relationships for 86 eleventh-grade students. Results revealed that formative performance was the strongest predictor of summative performance followed by self-confidence. Positive emotion revealed as having a positive indirect effect on summative performance through insight component. Considering for formative performance, self-confidence revealed as the strongest predictor followed by insight component. Self-confidence accounted as the only affective factor that directed to self-reflection components, need for and engagement in self-reflection. On the contrary, positive emotion accounted as the only affective factor that related to insight. Need for self-reflection was related to engagement in self-reflection, which in turn, related to insight. Need for selfreflection also mediated the relationship between self-confidence and engagement in self-reflection. Understand different mental processes within mathematics studies are important for future intervention exercises, especially for high school students.