Adult alcohol abstainers have a heightened risk of premature mortality compared to light-to-moderate drinkers. We examine three plausible explanations, other than lack of alcohol, for this observed difference: Abstainers 1) have early life disadvantages that undermine long-term health; 2) lack social support; 3) are less healthy. Method In the National Child Development Study, an ongoing national British cohort study of individuals born in 1958, we investigated whether early life disadvantages, lack of social support, and poor physical health reduce or eliminate the elevated risk of mortality through age 51 among those abstaining from alcohol at age 33. Using Cox proportional hazard models in a stepwise approach we examined whether the alcohol-mortality relationship changed when potential confounders were included. Results The risk of mortality by age 51 was greater among age-33 abstainers compared to light drinkers (Hazard Ratio [HR] = 2.18; 95% CI = 1.40, 3.40). Including early life disadvantages and social support in the hazard models did not alter these associations (HR = 2.12; 95% CI = 1.27, 3.54). Including physical health in the model resulted in a 25% reduction in risk of death among abstainers, though the difference in risk remained statistically significant (HR = 1.75; 95% CI = 1.04, 2.94). Conclusions Abstaining from alcohol in early adulthood, in comparison to light drinking, predicts increased risk for premature mortality, even after accounting for numerous early and young adult confounders. Future research should examine potential moderators of this association.