Effects of personalizing survey invitations on response rates have been extensively researched in the realm of mail surveys. Commonly, it is found that response rates increase when personalization is applied. Recently, efforts have been made to investigate whether these findings extend to the field of Web surveys that use e-mail invitations. Using data from a Web experiment conducted among first-year university students, personalization of e-mail invitations is shown to have significantly increased the response rate by 7.8 percentage points. From the theory that personalization decreases the level of anonymity and perceived privacy, differences in responses to sensitive questions were expected. However, no effects of personalization on the responses to a question probing for respondents’ sexual behavior were found.