Prior research (most of which is correlational) has suggested that activation of the parental care motivational system may lead people to make harsher moral judgments of social norm violators. We tested this hypothesis in 8 studies (total N = 1790). Seven of the studies were true experiments in which participants made moral judgments after being randomly assigned to either conditions designed to temporarily activate the parental care system or to a control condition. In one of these experiments, participants viewed photographs of either cute animals or furniture and in 6 additional experiments, participants engaged in an autobiographical writing task in which they recalled and wrote about a time they either cared for a child or—in the control conditions that varied across these experiments—had a different experience. In the final non-experimental study, women were recruited in public places and made moral judgments, the harshness of these judgments was compared between those accompanied by a young child versus not accompanied by a young child. The effects (and non-effects) of these procedures on moral judgments were inconsistent across the 8 studies and an internal meta-analysis of the 7 true experiments provided no compelling evidence that the experimental manipulations influenced moral judgments. We hope that these results offer some guidance to future researchers on what methods might—and might not—be effective in activating the parental care system and can support future work on the influence of parental care on moral cognition.