Revised Version -2 -Until the middle of the twentieth century, the discipline of political science was primarily qualitative -philosophical, descriptive, legalistic, and typically reliant on case studies that failed to probe causation in any measurable way. The word "science" was not entirely apt.In the 1950s, the discipline was transformed by the behavioral revolution, spearheaded by advocates of a more social scientific, empirical approach. Even though experimentation was the sine qua non of research in the hard sciences and in psychology, the method remained a mere curiosity among political scientists. For behavioralists interested in individual-level political behavior, survey research was the methodology of choice on the grounds that experimentation could not be used to investigate real-world politics (for more detailed accounts of the history of experimental methods in political science, see Bositis and Steinel 1987;Kinder and Palfrey 1993;Green and Gerber 2003).The consensus view was that laboratory settings were too artificial and that experimental subjects were too unrepresentative of any meaningful target population for experimental studies to be valid. Further, many political scientists viewed experiments --which typically necessitate the deception of research subjects --as an inherently unethical methodology.The bias against experimentation began to weaken in the 1970s when the emerging field of political psychology attracted a new constituency for interdisciplinary research. Laboratory experiments gradually acquired the aura of legitimacy for a small band of scholars working at the intersection of the two disciplines.1 Most of these 1 An important impetus to the development of political psychology was provided by the Psychology and Politics Program at Yale University. Developed by Robert Lane, the program provided formal training in psychology to political science graduate students -3 -scholars focused on the areas of political behavior, public opinion and mass communication, but there were also experimental forays into the fields of international relations and public choice (Hermann and Herman 1967;Riker 1967). Initially, these researchers faced significant disincentives to applying experimental methods --most importantly, research based on experiments was unlikely to see the light of day simply because there were no journals or conference venues that took this kind of work seriously.The first major breakthrough for political scientists interested in applying the experimental method occurred with the founding of the journal The unavailability of suitable laboratory facilities was but one of several obstacles facing the early experimentalists. An equally important challenge was the recruitment of experimental subjects. Unlike the field of psychology, where researchers could draw on a virtually unlimited captive pool of student subjects, experimentalists in political science had to recruit volunteer (and typically unpaid) subjects on their own initiative. Not only did this add to the costs of conduc...