The aim of this study was to test whether the association between belief in a just world (BJW) and Internet altruistic behavior (IAB) was mediated by gratitude and self-esteem in a sample of Chinese undergraduates. A total of 238 participants (aged from 18 to 25) completed a paper-and-pencil questionnaire which assessed their BJW, self-esteem, gratitude, and Internet altruistic behavior. Mplus 7.0 was used to conduct structural equation modeling to estimate direct and indirect effects. Path analysis showed that self-esteem and gratitude partially mediated the relationship between BJW and IAB. The final model also revealed a significant path from BJW thorough self-esteem and gratitude to IAB. Limitations and implications for research and practical application of the present study were discussed. (C) 2016 Elsevier Ltd. All rights reserved.