The paper discusses the problems and limitations of data collection through the Internet, dwelling on recent experiences. Online Population Censuses have several advantages compared with paper and face-to-face interviews. Questionnaires on the

Internet can be developed in a very user-friendly manner. The costs of data entry and data editing are much lower, the data are rapidly available and are of better quality. The experience of Singapore and Switzerland clearly demonstrate the feasibility of Electronic Censuses.

But there are also limitations. A central database with names and addresses as well as a centrally managed mail and password system are preconditions for the successful use of multi-modal data collection strategies (Singapore and Switzerland). Scaleable and flexible solutions, secure and powerful data connections as well as the permanent monitoring of online transactions are expensive. Major problems include also the lack public confidence with regard to confidentiality and the digital divide (USA, Switzerland). Population Censuses of the future (at least in highly developed countries) will probably follow a multi-modal strategy, combining register information, interviews by Internet, telephone and face-to-face.