Past studies that explored the antecedents of achievement goals have mostly focused on the role of personal characteristics and parental/teacher influences. However, the role of one's classmates has not been given much attention. Drawing on the concept of goal contagion, the present study aimed to examine whether classmates' achievement goals influence one's achievement goals. We recruited 848 secondary school students nested within 30 classes and asked them to answer relevant questionnaires at Time 1 and Time 2. Multilevel analysis was used to examine whether classmates' achievement goals at Time 1 predicted one's achievement goals at Time 2 thereby demonstrating achievement goal contagion. To rule out alternative explanations, we controlled for baseline achievement goals at Time 1, social desirability bias, and other relevant demographic factors. Results indicated that mastery-approach, performance-approach, and performance-avoidance goals were contagious, but mastery-avoidance goals were not. Our study highlights the importance of understanding achievement goal contagion among classmates.