Election administrators and public officials often consider changes in electoral laws, hoping that these changes will increase voter turnout and make the electorate more reflective of the voting-age population. The most recent of these innovations is voting-by-mail (VBM), a procedure by which ballots are sent to an address for every registered voter. Over the last 2 decades, VBM has spread across the United States, unaccompanied by much empirical evaluation of its impact on either voter turnout or the stratification of the electorate. In this study, we fill this gap in our knowledge by assessing the impact of VBM in one state, Oregon. We carry out this assessment at the individual level, using data over a range of elections. We argue that VBM does increase voter turnout in the long run, primarily by making it easier for current voters to continue to participate, rather than by mobilizing nonvoters into the electorate. These effects, however, are not uniform across all groups in the electorate. Although VBM in Oregon does not exert any influence on the partisan composition of the electorate, VBM increases, rather than diminishes, the resource stratification of the electorate. Contrary to the expectations of many reformers, VBM advantages the resource-rich by keeping them in the electorate, and VBM does little to change the behavior of the resource-poor. In short, VBM increases turnout, but it does so without making the electorate more descriptively representative of the voting-age population.