Although survey researchers often use mixed-mode surveys to help reduce particular forms of survey error, speed up data collection, or lower costs (de Leeuw, 2005; Pierzchala, 2006), current research is unclear which sequence of modes is most effective. Once the survey is in field, it is also not clear which method of non-response prompting is best. Reminder postcards are a well-accepted strategy for prompting non-respondents to complete questionnaires (Dillman et al, 2008), although recent research suggests using an automated phone message can be an effective (and cheaper) prompting tool (Census, 2004). However, it is not clear which method results in the highest response rate (McCarthy, 2007; McCarthy, 2008). Furthermore, there is little literature on the efficacy of live interviewer prompting as compared to automated messages or postcards. In order to address these questions, experiments were embedded in the administration of the 2010 IRS Individual Taxpayer Burden Survey. The experiment compared mode sequence as well as non-response prompting. At the initial contact, approximately one-quarter of the sample received a mailed hard copy invitation to the web survey, while the remainder received the paper survey. A reminder prompt for the entire sample was then followed by a mailing of the paper survey to all non-respondents. For the final contact, 40% of non-respondents received a paper survey by express mail, 20% received an automated telephone prompt, and the remaining 40% received a telephone prompt from a human interviewer. Our analysis will examine the results of the experiment to answer two questions: (1) Which mode should we offer first to maximize response rates and minimize costs; and (2) Which final method of non-response prompting yields the highest response rate at the lowest cost? Whenever feasible, we will include demographic variables in the analysis to determine which contact strategies are most effective for which groups.