Barbara Sinclair provides a concise definition of agenda setting: "the process through which issues attain the status of being seriously debated by politically relevant actors" (1986, p. 35). The study of agenda setting began as a reaction to the pluralist claim that policy outcomes are the result of competing groups (Dahl 1956, 1961; Truman 1951). E. E. Schattschneider (1960) claimed that groups would not necessarily form on both sides of an issue, given the upper-class bias in the system. Theodore Lowi (1979) highlighted this problem of imperfect competition, arguing that what gets on the congressional agenda is a process of bargaining between a few interested groups, elected officials, and administrators. Finally, Peter Bachrach and Morton Baratz (1969) argued that many issues would be relegated to nondecision-making because leaders only put safe issues on the agenda.
The next logical question is how agenda setting is achieved. Early scholars argued that an item is more likely to get on the agenda as the scope of conflict expands (Schattschneider 1960) and as the groups involved become larger (Cobb and Elder 1972). In John Kingdon’s (1984) model, what gets on the agenda is a function of problem and political streams (the proposal stream presents the alternatives), where policy entrepreneurs play a key role in using their resources to push problems onto the agenda. Frank Baumgartner and Bryan Jones (1993) added to this understanding by claiming that strategic actors not only push items onto the agenda through issue definition (Riker 1986; Stone 1988) but also through the choice of policy venues.
Scholars have investigated the role of various actors in setting the agenda. Researchers have found that in the U.S. government the president is more likely to influence the congressional agenda on foreign policy issues (Peake 2001; Peterson 1994), under conditions of unified control (Taylor 1998), when he makes explicit appeals to the public (Kernell 1986) or when his political capital is high (Light 1982; Mueller 1973). Scholars of the U.S. Congress have shown that the majority party exerts negative and positive agenda control through the powers of the speaker (Cox and McCubbins 1993, 2002; also see Riker 1982). Gregory Caldeira and John Wright (1988) find that amicus curiae briefs influence whether the Supreme Court grants writs of certiorari. The media plays an agenda-setting role by influencing public perceptions about which issues are important (Iyengar and Kinder 1987; McCombs and Shaw 1972; MacKuen 1984), which in turn influences the standards used to evaluate leaders (Miller and Krosnick 2000), and by influencing preferences by framing issues (Druckman 2001; Iyengar 1987). While women and minority groups have had a harder time influencing the agenda, issues of concern to these groups are more likely to make it onto the agenda, given strong group organization, innovative policy proposals, and the presence of minorities and women in elected office (Bratton and Haynie 1999; Epstein, Niemi, and Powell 2005; McClain 1990, 1993; Miller 1990; Thomas 1994).
One of the key consequences of agenda setting is that many issues do not make it onto the agenda. This facet leads to the punctuated equilibrium model of Baumgartner and Jones (1993), where long periods of stability on an issue, are seen, followed by an abrupt shift to a new equilibrium, which can be reached as the issue becomes salient and institutional actors benefit from a new alternative.
