For many years, scholars of voting behavior have been thwarted in their attempts to identify micro spatial variations in turnout by data limitations. This has meant that most analyses have been ecological, which has implications for valid inference. Here, for the first time, a hierarchical approach is used to show the relative importance of several micro spatial scales, including the household, on voter participation. The findings highlight the importance of the household context. While those who live together often turn out together, the relative level of clustering within households as opposed to between geographical areas is found to be more important for two-person households compared to other households. Even after taking account of whether individuals are likely to self-select others from similar social backgrounds or with similar political attitudes, there is strong evidence of large and significant household effects on voter participation. © 2009, Midwest Political Science Association.