Objective Where population subgroups have distinctly “young” or “old” adult age distributions, their observed overall rates of political participation may differ for this demographic reason. Age standardization can quantify the proportion of an observed difference in registration rates attributable to age structural differences between two populations, thereby facilitating comparison of political participation across subgroups. Methods I illustrate the derivation and interpretation of an age‐standardized registration rate. This rate weights a set of observed age‐specific registration rates with a standard age distribution to create a hypothetical total (all‐ages) registration rate, to afford an undistorted comparison of Hispanic and non‐Hispanic white voter registration. Results For seven communities studied here, differences in adult age structure account for as much as one‐third of the observed difference in the voter registration rates of adult Hispanics and non‐Hispanic whites in a community. The effect of age structure is most apparent in those communities registering substantial influxes of young‐adult Hispanics. Conclusion Age standardization is a useful technique to control for differences in population structure that may obscure a comparison of political participation across subgroups.