In the last few years, it has become possible to conduct meaningful behavioral research via the Internet. As of June 17, 1998, there were 35 Internet experiments and surveys in the American Psychological Society list of Psychological Research on the Net, maintained by John Krantz, URL [http://psych.hanover.edu/APS/exponnet.html]. By May 11, 1999, this figure had grown to 65, suggesting a growth rate of about 100% per year. I expect that this book and others like it will accelerate this growth. Of the experiments listed in the APS Web site, there were 24 in social psychology, 13 in cognitive, 8 in sensation/perception, 5 in health psychology, 4 in developmental, 3 in clinical, 3 in personality and industrial-organizational, 2 in biological, 2 in emotions, and one in general psychology. Although this list does not include all experiments, it gives a proportional estimate that indicates the growth of research conducted via the Web. Early "pioneers" of Internet research soon learned that it was not only possible to conduct research this way, but that it was also feasible to collect large samples of high quality data in a short period of time. This book is intended for psychologists who are interested in learning from the experiences of those who have been engaged in this type of research. The book includes a great deal of good advice from those who have learned by experience. In reading the book, you should follow suggested links on your computer, which should be your window to the Web and your study companion. This Web page includes the most important links from the book, which will save you the trouble of typing in the URLs (the addresses of the sites on the Web). One advantage of Web-based research is the ease with which another can see exactly what the participants experienced and also learn how the experimenter carried it out. To save space (and trees), the authors have made a great deal of information available to you electronically via the Internet. Terms used in the book unique to this type of research (e.g., HTTP, HTML, FTP, etc.) are defined in a glossary at the end of the book. The book has three sections. The first deals with general questions such as do the results of Web experiments agree with those of laboratory experiments? Who are the people who volunteer to participate via the Internet? What were the developments that led to the first Web studies and what did the early Web researchers experience? What are the methodological considerations in doing research by "remote control?" The second section considers studies of individual differences and cultural differences. Because the Internet provides a means to reach large and diverse samples, it seems ideally suited for these purposes. The third section covers advanced computer techniques that allow for greater control of Internet experiments. These include the dynamic creation and display of graphics, randomization, and timing in experiments such as those in cognitive experimental psychology. In addition, methods for scoring and feedback on surveys or tests, tracking of participants, security, and saving of data on the server are discussed.