effects in both earlier and later cohorts, then the association cannot be explained by age at assessment or by trends that moved in the same direction across both periods. In another set of analyses, we limit the sample to subjects who were coming of age within two years of a change in MLDA law affecting 20-year olds. In this age-restricted sample, respondents in each state/period cell are very closely matched in demographic characteristics, and are likely to have experienced similar exposures to other economic, social, cultural or political trends. In both the full and age-restricted sample, we test whether the MLDA laws are likely to be working through age of initiation, per se, by evaluating the change in the MLDA estimate in models that control for lifetime abstention status and age of onset of regular drinking. Overall, we find that earlier age at drinking initiation predicts higher risk of past-year alcohol or substance use disorder, and exposure to a lower minimum legal purchase age predicts higher risk of a past-year alcohol or other substance use disorder, even when respondents are evaluated in their 40’s or 50’s., However, the MLDA association does not seem to be explained by self-reported age of
