Social comparison is prevalent, even within classrooms, yet limited research explores its impact on academic outcomes. The current study adopted social comparison theory and achievement goal theory and tested a structural equation model that explained the pathways among two types of social comparison (i.e. ability-based and opinion-based), achievement goals, self-efficacy, effort, and academic grades. Based on a sample of 398 high school students, the current study demonstrated associations between opinion-based social comparison and mastery goals and between ability-based social comparison and performance goals. Furthermore, the current study identified different pathways for the indirect effects of social comparison and achievement goals that contributed to academic grades. The findings yielded the learning-oriented pathways and the performance-oriented pathways. The learning-oriented pathways showed the connections among opinion-based social comparison, mastery-approach goals, internal learning capacities (i.e. self-efficacy and effort), and academic grades; whereas the performance-oriented pathways demonstrated the connections among ability-based social comparison, performance-approach goals, and academic grades. This study implies that having a balanced mind-set between learning-oriented and performance-oriented approaches would benefit students most. Parents and teachers can play pivotal roles in nurturing students to focus on their internal learning processes within the competitive environment. The implications of competition-based achievement in classrooms are discussed.