We propose that gratitude norms function to motivate people to express system-justifying beliefs and attitudes. When people feel grateful for the benefits they receive from sociopolitical institutions, they may feel compelled to express their appreciation by self-censoring any grievances they may have about the functioning of their system. We review theory and research on the psychology of gratitude and integrate it with theory and research on the system-justification motive. We illustrate how new insights into various effects in the literature on ideology and system justification might be gained by considering how the expression of system-justifying opinions might function as an expression of gratitude toward one's system. We speculate that this system-justifying function of gratitude is a consequence of social norms that overgeneralize the domain of gratitude from the context of interpersonal relations between peers to the context of relations with the larger, impersonal systems that govern people's lives.