For Kollman, outside lobbying is any attempt by interest group leaders to affect public policy by making use of citizen contacts or pressure. Thus, outside lobbying encompasses press conferences, letter-writing campaigns, and protests, as well as tactics like political advertising and congressional visits by corporate leaders. He views this type of lobbying as normatively important because “it is a common means (perhaps the most common means except for elections) for elite policymakers to experience pressure in the form of popular participation” (8). But in a theme that Kollman returns to throughout the book, he acknowledges that it is clearly an empirical question whether outside lobbying accurately reflects popular support of an issue.

Kollman begins with a sample of 50 organized interests with offices in Washington, DC, and interviews their leaders about their outside lobbying activities on issues related to 77 public opinion poll questions from 1991 and 1992. Most groups were involved in multiple issues, resulting in 323 group-issue cases to analyze. In addition, Kollman interviews leaders who lobbied regarding the North American Free Trade Agreement in 1993 and health care in 1993 and 1994, and he provides a case study of NAFTA in the book’s penultimate chapter.

Outside lobbying serves two distinct purposes, Kollman argues: it acts as a signal to policy makers about the level of public support that a policy enjoys, and it attempts to increase the level of that support through conflict expansion. Within the signaling process, there are two dimensions of public opinion to be conveyed: the salience of the issue and the popularity of the group’s policy position. Interest groups play an especially important role in communicating salience to politicians, Kollman says, because while preferences on particular issues are relatively stable and relatively easy to determine via opinion polls, the salience of particular issues to particular constituents is not so obvious.

Kollman provides a formal model of this signaling process that distinguishes between “high type” groups whose constituents really do care strongly about the issue in question and “low type” groups whose constituents do not care. Truth confers an advantage in this game since the higher the true salience of the issue to the group, the lower the costs are for the group to engage in outside lobbying. Astroturf can be bought, but it is much more expensive than a spontaneous outpouring of strongly felt grassroots support. Unfortunately, Kollman notes, “on average groups without popular support are the ones who can afford” to buy it (161), making the advantage truth possesses less comforting than it might otherwise be.

Using the polls to measure popularity and National Election Study “most important problem” questions to assess salience, Kollman finds that popularity is only weakly related to outside lobbying, while the relationship with salience is somewhat stronger. The results vary, however, depending on the stage of the policy process. For issues that have not yet reached the congressional agenda, for example, the conflict expansion role (including education of the public) of outside lobbying is more important than the signaling role, and the relationship with existing popularity and salience is weaker. Policy popularity and salience are most important to the decision to use outside lobbying when the issue is before a congressional committee (what Kollman calls the agenda shaping stage), declining again during the debate and voting stage.

Kollman’s findings in general show that outside lobbying tends more toward legitimacy than illegitimacy—that is, outside lobbying campaigns tend to correlate positively with public opinion. The implications of the results are not, however, entirely benign. The level of financial resources that an organization has is always at least as important as the popularity or salience of an issue in the decision to use outside lobbying. And when Kollman truncates the data to consider only those organizations that engaged in at least some outside lobbying activities, the effect of resources on the extent of the outside lobbying campaign is more than three times as great as that of the popularity or salience.

Kollman’s well-designed study brings us closer to understanding how interest groups adapt their lobbying strategies across issues, but many questions remain unanswered. Outside Lobbying includes no issues that are truly off the agenda, in that all of the issues were at least prominent enough to be the focus of a national opinion poll. How do issues off the public radar screen differ from the ones Kollman studied? Under what circumstances do groups succeed in pushing such issues onto the agenda? How much effect do these outside lobbying campaigns have on the public salience of issues? There is much to learn about interest group lobbying strategies and the implications of these strategies for policy making in a democracy, but Kollman’s book provides a solid first step.