In the last decade it has become possible to collect data from participants who are tested via the WWW rather than in the lab.  Although this mode of research has some inherent limitations due to lack of control and observation of conditions, it also has a number of advantages over lab research.  Many of the potential advantages have been well-described in a number of publications (Birnbaum, 1999b; 2000a; 2000b; 2001a; 2001b; 2004a; 2004b; Krantz & Dalal, 2000; Reips, 1995; 1997; 1999; 2000; 2001a; 2001b; Reips & Bosnjak, 2001; Schmidt, 1997a; 1997b).  Some of the chief advantages are that (1) one can test large numbers of participants very quickly; (2) one can recruit large heterogeneous samples and people with rare characteristics; (3) the method is more cost-effective in time, space, and labor in comparison with lab research. This chapter will provide an introduction to the major features of the new approach and illustrate the most important techniques in this area of research.