Research on misconduct in science has largely focused on egregious violations such as fabrication, falsification, and plagiarism. Recent scholarship, however, calls for greater attention to forms of everyday misconduct and how scientists navigate ethical ambiguity when they are unable or unwilling to make formal accusations. Drawing on interview data from 251 physicists and biologists from both elite and non-elite universities and research institutes in the United States, United Kingdom, and India, we find that scientists are often reticent or unable to take formal action against many behaviors they perceive as unethical and irresponsible. As a result, they resort to informal gossip to warn colleagues of transgressors. Many express confidence that such pro-social gossip can serve as a means of social control by tarnishing the reputations of transgressors. Yet its effectiveness as a form of social control is limited, particularly when transgressors enjoy higher status than gossipers. We identify two types and three consequences of such gossip and assess the effectiveness of gossip as a means of social control. Finally, we consider the implications of our study for understanding and decreasing misconduct in science.