Two studies are presented that examine disclosure of sensitive information and personalization in Internet-based surveys. In the first study, the impact of a personalized salutation on two forms of non-disclosure to a sensitive personal question (salary level) is tested. The results revealed that a personalized salutation tends to increase levels of active non-disclosure (measured through use of an 'I prefer not to answer' option), but not passive non-disclosure (where the respondent selects no option). In the second study, participants are directed to the survey via either a personalized URL (which incorporated an encoded identifier) or via a secure log-on page. Non-disclosure to a sensitive question (salary) was significantly higher when participants went through a log-on procedure. We suggest that this pattern of non-disclosure to sensitive questions reflects increases in identifiability when a personalized salutation or log-on procedure is used. We further suggest that the provision of an active non-disclosure option to a sensitive question is particularly appropriate in contexts in which anonymity may be compromised, since it enables participants to both protect their privacy and respond appropriately to the survey.