We addressed the relation between nostalgia and moral judgment or behavior. We hypothesized that nostalgia, a social emotion, increases moral concern (H1), nostalgia intensifies punitiveness against moral transgressors (H2), and that the nostalgia—punitiveness link is mediated by moral concern (H3). We conducted three cross-sectional (Studies 1, 2, 4) and one experimental (Study 3) investigations (N = 1145). The investigations, involving distinct operationalizations of the relevant constructs (nostalgia, moral concern, punitiveness) and diverse samples (U.S., Canadian, and European Prolific workers, French business school students, Dutch community members), yielded results consistent with the hypotheses. Nostalgia keeps one’s moral compass in check. The findings enrich the emotions and morality literatures.