In this article, we present results from a study of how varying e-mail ‘‘cover letters’’ in the implementation of an online survey can influence response rates. Historically, there is little evidence that the content of survey cover letters has a strong effect on response rates in off-line survey environments (Harvey, 1987), although empirical research on this question is limited and some research has pointed to small, but significant, effects due to varying letter content (see Brennan, 1992; Redline, Oliver, & Fecso, 2004). Online self-completion surveys differ from paper versions in that the link that survey targets must click on to complete the survey is embedded in the ‘‘cover letter’’ e-mail. As such, we have reason to suspect that the content of such e-mails may affect the likelihood that targets respond to the survey and influence the quality of the responses that they provide.