Web surveys have serious shortcomings in terms of their representativeness, but they appear to have some good measurement properties. This talk focuses on the general features of web surveys that affect data quality, especially the fact that they are primarily visual in character. In addition, it examines the effectiveness of web surveys as a form of self-administration. A number of experiments have compared web surveys with other modes of data collection. A meta-analysis of these studies shows that web surveys maintain the advantages of traditional forms of self-administration; in particular, they reduce social desirability bias relative to interviewer administration of the questions. I conclude by discussing some likely future developments in web surveys—their incorporation of avatars as “virtual interviewers” and the increasing use of mobile devices (such as tablet computers and smart phones) to access and complete web survey.