Many economists and educators of diverse political beliefs favor public support for education on the premise that a more educated electorate enhances the quality of democracy. While some earlier studies document an association between schooling and citizenship, little attempt has been made to address the possibility that unobservable characteristics of citizens underlie this relationship. This paper explores the effect of extra schooling induced through compulsory schooling laws on the likelihood of becoming politically involved in the US and the UK. We find that educational attainment is related to several measures of political interest and involvement in both countries. For voter turnout, we find a strong and robust relationship between education and voting for the US, but not for the UK. Using the information on validated voting, we find that misreporting of voter status can not explain our estimates. Our results suggest that the observed drop in voter turnout in the US from 1964 to 2000 would have been 10.4 to 12.3 percentage points greater if high school attainment had stayed at 1964 rates, holding all else constant. However, when we condition on registration, our US results approach the UK findings. This may indicate that registration rules present a barrier to low-educated citizens' participation.