(Table is included in full-text article). Internet-based questionnaires will, no doubt, continue to gain popularity. Internet presents an attractive medium for the researcher to collect large amounts of data with relatively little effort. The questionnaires can be available to respondents all over the world, 24 h a day, with very little labor involved. The questionnaires can be electronically scored immediately upon completion. Results can then be stored in an analyzable form or be used instantly to redirect the respondent to follow-up questionnaires. Nonetheless, good questionnaire design and psychometric principles still apply. This is true even when porting a valid paper and pencil test to the Internet. In addition, technical and logistical issues in web-based testing can affect the reliability and validity of the questionnaires. Researchers are cautioned to follow good questionnaire development practices and consider the unique problems of Internet-based instruments.