Social goals, such as prosocial and social responsibility goals, are crucial predictors of learning and optimal functioning. Past studies on social goals have usually focused on how teachers and peers influence social goal pursuit. However, the role of social contagion among classmates has seldom been explored. This study aimed to test the social contagion of social goals (prosocial and social responsibility goals) among classmates and the implications this might have on students' engagement in school. We recruited 1524 students nested within 50 classes and asked them to respond to surveys across two time points. Multilevel path analysis was used to analyze the data. Students embedded in classes with higher social goals at Time 1 had higher social goals themselves at Time 2, demonstrating social contagion effects. Social contagion effects remained robust despite controlling for auto-regressor effects and other alternative explanations. Higher social goals (prosocial and social responsibility), in turn, were positively associated with greater engagement. This study has important implications for theorizing on social goals and highlights the need to examine the important role played by social contagion in understanding motivational processes.