On-pack tobacco warnings typically feature long-term health risks, which many young adults rationalize or reject. We examined the emotions generated by more proximal warnings to see if we could identify common features among the most effective warnings. Respondents in a sample of 474 smokers and 476 susceptible non-smokers used a modified Geneva Emotion Wheel (GEW) to assess cigarette packs displaying 12 test warnings and one current warning. The strongest emotions aroused in smokers were disgust, disappointment, and regret. Three warnings showing the effect of smoking on babies and animals had significantly higher emotional potency scores than a current health warning. Among susceptible non-smokers, warnings showing harm to animals, child labor, and a dying smoker had the highest emotional potency. Stronger negative emotions were elicited from both smokers and susceptible non-smokers by warnings that featured more proximal outcomes than are typically shown in on-pack tobacco warnings. On-pack warnings that resonate with young people, the group most at risk of smoking and most likely to benefit from quitting, could promote cessation and deter initiation more effectively than warnings depicting long-term health outcomes. The GEW could be used to screen potential warning images to identify those most likely to be worth evaluating.