The results of an application of Internet survey methods to a household travel diary project are described. The project included a full field application of an Internet-based household travel diary instrument in a split sample design with conventional telephone or mail administration. The effects of this type of administration on survey response and on survey data are described. The work described demonstrates how Internet-based travel diary instruments can be used to complement other, more traditional survey approaches. The Internet household travel diary instrument used included several features that take advantage of the computational power provided by modern servers and the graphical user interface provided by web browsers. Among these, the most important are detailed internal consistency checks that test the continuity and completeness of the activity and trip logs and interactive geocoding of trip ends. The response rates in the split sample conducted for the Las Cruces application indicate that providing an Internet option had a small positive effect. However, there are more pronounced effects on reported trip making—more trips reported in the Internet instrument—and on item nonresponse—lower rates with the Internet instrument. Overall, respondents who used the Internet instrument found it easy to use and appreciated having the option to complete the questionnaire at their convenience. There are clear areas for further research, but it is equally clear that Internet-based household diary surveys can provide an important, cost-effective complement to computer-assisted telephone interview and mail methods.