All survey respondents may not share the same interpretation of the privacy assurances made to them by survey sponsors. Investigating the antecedents to anonymity perceptions helps to identify what may influence a survey respondent’s candor. The current study examined the influence of environmental and dispositional antecedents on anonymity perceptions in a Web-based survey. Participants completed an anonymous survey through the Internet that measured trust, evaluation apprehension, and anonymity perceptions. Respondents also described their physical and electronic environment. Physical environment and dispositional trust were found to predict ratings of anonymity perceptions.