Abstract: In This study we investigate the mediating role of achievement goals and reflective thinking in relation between classroom environment and performance. The data was collected from 500 girls who were studying in high school. This sample was selected by multistage cluster sampling. Questionnaires have been administrated. academic performance was assessed by grades in mathematics. Data analysis indicated that the components of the classroom environment-involvement, student cohesiveness, task orientation- exerted direct and indirect influences on achievement goals, reflective thinking and student’s performance in mathematics. Findings evidently show that direct effect of students’ involvement on performance – approach goals is significant and involvement in assignment and class activity is a unique component which has a significant direct effect on math performance. Direct effect of cohesiveness on performance avoidance goals, task orientation on reflect and habitual act, mastery goals on understanding and critical thinking, performance approach on habitual act is significant. Totally, these results show that classroom environment- involvement component, cohesiveness and task orientation have direct and indirect effect on achievement goals, reflective thinking and student performance in mathematics. However we need further evidence to clarify some ambiguities.