Although political scientists have begun to investigate the properties of Internet surveys, much remains to be learned about the utility of the Internet mode for conducting major survey research projects such as national election studies. This paper addresses this topic by presenting the results of an extensive survey comparison experiment conducted as part of the 2005 British Election Study. Analyses show statistically significant, but generally small, differences in distributions of key explanatory variables in models of turnout and party choice. Estimating model parameters reveals that there are few statistically significant differences between coefficients generated using the in-person and Internet data, and the relative explanatory power of rival models is virtually identical for the two types of data. In general, the in-person and Internet data tell very similar stories about what matters for turnout and party preference in Britain. Determining if similar findings obtain in other countries should have high priority on the research agenda for national election studies.